Use cookies for thread identification instead of pointers directly which gives a buffer against wrongly identifying a thread when the slot is recycled (which has been nagging me for awhile). A slot gets 255 uses before it repeats. Everything gets incompatible so a full update is required.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19377 a1c6a512-1295-4272-9138-f99709370657

32 files changed, 329 insertions, 234 deletions

diff --git a/apps/buffering.c b/apps/buffering.c
index dfc90065d6..6160869498 100644
--- a/apps/buffering.c
+++ b/apps/buffering.c
@@ -184,7 +184,7 @@ enum {
 static void buffering_thread(void);
 static long buffering_stack[(DEFAULT_STACK_SIZE + 0x2000)/sizeof(long)];
 static const char buffering_thread_name[] = "buffering";
-static struct thread_entry *buffering_thread_p;
+static unsigned int buffering_thread_id = 0;
 static struct event_queue buffering_queue;
 static struct queue_sender_list buffering_queue_sender_list;
 
@@ -1468,13 +1468,13 @@ void buffering_init(void)
     conf_watermark = BUFFERING_DEFAULT_WATERMARK;
 
     queue_init(&buffering_queue, true);
-    buffering_thread_p = create_thread( buffering_thread, buffering_stack,
+    buffering_thread_id = create_thread( buffering_thread, buffering_stack,
             sizeof(buffering_stack), CREATE_THREAD_FROZEN,
             buffering_thread_name IF_PRIO(, PRIORITY_BUFFERING)
             IF_COP(, CPU));
 
     queue_enable_queue_send(&buffering_queue, &buffering_queue_sender_list,
-                            buffering_thread_p);
+                            buffering_thread_id);
 }
 
 /* Initialise the buffering subsystem */
@@ -1501,7 +1501,7 @@ bool buffering_reset(char *buf, size_t buflen)
     high_watermark = 3*buflen / 4;
 #endif
 
-    thread_thaw(buffering_thread_p);
+    thread_thaw(buffering_thread_id);
 
     return true;
 }
diff --git a/apps/codecs.h b/apps/codecs.h
index 4194524e6d..d765daba2a 100644
--- a/apps/codecs.h
+++ b/apps/codecs.h
@@ -82,12 +82,12 @@
 #define CODEC_ENC_MAGIC 0x52454E43 /* RENC */
 
 /* increase this every time the api struct changes */
-#define CODEC_API_VERSION 27
+#define CODEC_API_VERSION 28
 
 /* update this to latest version if a change to the api struct breaks
    backwards compatibility (and please take the opportunity to sort in any
    new function which are "waiting" at the end of the function table) */
-#define CODEC_MIN_API_VERSION 27
+#define CODEC_MIN_API_VERSION 28
 
 /* codec return codes */
 enum codec_status {
@@ -164,14 +164,14 @@ struct codec_api {
     void (*yield)(void);
 
 #if NUM_CORES > 1
-    struct thread_entry *
+    unsigned int
         (*create_thread)(void (*function)(void), void* stack,
                          size_t stack_size, unsigned flags, const char *name
                          IF_PRIO(, int priority)
                          IF_COP(, unsigned int core));
 
-    void (*thread_thaw)(struct thread_entry *thread);
-    void (*thread_wait)(struct thread_entry *thread);
+    void (*thread_thaw)(unsigned int thread_id);
+    void (*thread_wait)(unsigned int thread_id);
     void (*semaphore_init)(struct semaphore *s, int max, int start);
     void (*semaphore_wait)(struct semaphore *s);
     void (*semaphore_release)(struct semaphore *s);
diff --git a/apps/codecs/mpa.c b/apps/codecs/mpa.c
index 7732622383..37a1afadfa 100644
--- a/apps/codecs/mpa.c
+++ b/apps/codecs/mpa.c
@@ -200,7 +200,7 @@ static void set_elapsed(struct mp3entry* id3)
 static int mad_synth_thread_stack[DEFAULT_STACK_SIZE/sizeof(int)/2] IBSS_ATTR;
 
 static const unsigned char * const mad_synth_thread_name = "mp3dec";
-static struct thread_entry *mad_synth_thread_p;
+static unsigned int mad_synth_thread_id = 0;
 
 
 static void mad_synth_thread(void)
@@ -249,14 +249,14 @@ static bool mad_synth_thread_create(void)
     ci->semaphore_init(&synth_done_sem, 1, 0);
     ci->semaphore_init(&synth_pending_sem, 1, 0);
        
-    mad_synth_thread_p = ci->create_thread(mad_synth_thread, 
+    mad_synth_thread_id = ci->create_thread(mad_synth_thread, 
                             mad_synth_thread_stack,
                             sizeof(mad_synth_thread_stack), 0,
                             mad_synth_thread_name 
                             IF_PRIO(, PRIORITY_PLAYBACK)
                             IF_COP(, COP));
     
-    if (mad_synth_thread_p == NULL)
+    if (mad_synth_thread_id == 0)
         return false;
 
     return true;
@@ -267,7 +267,7 @@ static void mad_synth_thread_quit(void)
     /*mop up COP thread*/
     die=1;
     ci->semaphore_release(&synth_pending_sem);
-    ci->thread_wait(mad_synth_thread_p);
+    ci->thread_wait(mad_synth_thread_id);
     invalidate_icache();
 }
 #else
diff --git a/apps/codecs/spc.c b/apps/codecs/spc.c
index 380cfbdb8b..14d28dfca8 100644
--- a/apps/codecs/spc.c
+++ b/apps/codecs/spc.c
@@ -197,7 +197,7 @@ static int spc_emu_thread_stack[DEFAULT_STACK_SIZE/sizeof(int)]
     CACHEALIGN_ATTR;
 
 static const unsigned char * const spc_emu_thread_name = "spc emu";
-static struct thread_entry *emu_thread_p;
+static unsigned int emu_thread_id = 0;
 
 enum
 {
@@ -352,11 +352,11 @@ static void spc_emu_thread(void)
 
 static bool spc_emu_start(void)
 {
-    emu_thread_p = ci->create_thread(spc_emu_thread, spc_emu_thread_stack,
+    emu_thread_id = ci->create_thread(spc_emu_thread, spc_emu_thread_stack,
                            sizeof(spc_emu_thread_stack), CREATE_THREAD_FROZEN,
                            spc_emu_thread_name IF_PRIO(, PRIORITY_PLAYBACK), COP);
 
-    if (emu_thread_p == NULL)
+    if (emu_thread_id == 0)
         return false;
 
     /* Initialize audio queue as full to prevent emu thread from trying to run the
@@ -368,7 +368,7 @@ static bool spc_emu_start(void)
     sample_queue.tail = 2;
 
     /* Start it running */
-    ci->thread_thaw(emu_thread_p);
+    ci->thread_thaw(emu_thread_id);
     return true;
 }
 
@@ -382,10 +382,10 @@ static inline int load_spc_buffer(uint8_t *buf, size_t size)
 
 static inline void spc_emu_quit(void)
 {
-    if (emu_thread_p != NULL) {
+    if (emu_thread_id != 0) {
         emu_thread_send_msg(SPC_EMU_QUIT, 0);
         /* Wait for emu thread to be killed */
-        ci->thread_wait(emu_thread_p);
+        ci->thread_wait(emu_thread_id);
         invalidate_icache();
     }
 }
diff --git a/apps/pcmbuf.c b/apps/pcmbuf.c
index c7db4d3101..9ca5fbf5cf 100644
--- a/apps/pcmbuf.c
+++ b/apps/pcmbuf.c
@@ -115,7 +115,7 @@ static bool pcmbuf_flush;
 static int codec_thread_priority = PRIORITY_PLAYBACK;
 #endif
 
-extern struct thread_entry *codec_thread_p;
+extern uintptr_t codec_thread_id;
 
 /* Helpful macros for use in conditionals this assumes some of the above
  * static variable names */
@@ -258,13 +258,13 @@ static void boost_codec_thread(bool boost)
         if (priority != codec_thread_priority)
         {
             codec_thread_priority = priority;
-            thread_set_priority(codec_thread_p, priority);
+            thread_set_priority(codec_thread_id, priority);
             voice_thread_set_priority(priority);
         }
     }
     else if (codec_thread_priority != PRIORITY_PLAYBACK)
     {
-        thread_set_priority(codec_thread_p, PRIORITY_PLAYBACK);
+        thread_set_priority(codec_thread_id, PRIORITY_PLAYBACK);
         voice_thread_set_priority(PRIORITY_PLAYBACK);
         codec_thread_priority = PRIORITY_PLAYBACK;
     }
@@ -276,7 +276,7 @@ static void pcmbuf_under_watermark(void)
     /* Only codec thread initiates boost - voice boosts the cpu when playing
        a clip */
 #ifndef SIMULATOR
-    if (thread_get_current() == codec_thread_p)
+    if (thread_get_current() == codec_thread_id)
 #endif /* SIMULATOR */
     {
 #ifdef HAVE_PRIORITY_SCHEDULING
diff --git a/apps/playback.c b/apps/playback.c
index 50c4017200..3aed12e918 100644
--- a/apps/playback.c
+++ b/apps/playback.c
@@ -299,7 +299,7 @@ static struct queue_sender_list codec_queue_sender_list;
 static long codec_stack[(DEFAULT_STACK_SIZE + 0x2000)/sizeof(long)]
 IBSS_ATTR;
 static const char codec_thread_name[] = "codec";
-struct thread_entry *codec_thread_p; /* For modifying thread priority later. */
+unsigned int codec_thread_id; /* For modifying thread priority later. */
 
 /* PCM buffer messaging */
 static struct event_queue pcmbuf_queue SHAREDBSS_ATTR;
@@ -2499,7 +2499,7 @@ static void audio_thread(void)
  */
 void audio_init(void)
 {
-    struct thread_entry *audio_thread_p;
+    unsigned int audio_thread_id;
 
     /* Can never do this twice */
     if (audio_is_initialized)
@@ -2543,22 +2543,22 @@ void audio_init(void)
        talk first */
     talk_init();
 
-    codec_thread_p = create_thread(
+    codec_thread_id = create_thread(
             codec_thread, codec_stack, sizeof(codec_stack),
             CREATE_THREAD_FROZEN,
             codec_thread_name IF_PRIO(, PRIORITY_PLAYBACK)
             IF_COP(, CPU));
 
     queue_enable_queue_send(&codec_queue, &codec_queue_sender_list,
-                            codec_thread_p);
+                            codec_thread_id);
 
-    audio_thread_p = create_thread(audio_thread, audio_stack,
+    audio_thread_id = create_thread(audio_thread, audio_stack,
                   sizeof(audio_stack), CREATE_THREAD_FROZEN,
                   audio_thread_name IF_PRIO(, PRIORITY_USER_INTERFACE)
                   IF_COP(, CPU));
 
     queue_enable_queue_send(&audio_queue, &audio_queue_sender_list,
-                            audio_thread_p);
+                            audio_thread_id);
 
 #ifdef PLAYBACK_VOICE
     voice_thread_init();
@@ -2599,8 +2599,8 @@ void audio_init(void)
 #ifdef PLAYBACK_VOICE
     voice_thread_resume();
 #endif
-    thread_thaw(codec_thread_p);
-    thread_thaw(audio_thread_p);
+    thread_thaw(codec_thread_id);
+    thread_thaw(audio_thread_id);
 
 } /* audio_init */
 
diff --git a/apps/plugin.c b/apps/plugin.c
index de2dd3f7c7..e55ecd46a7 100644
--- a/apps/plugin.c
+++ b/apps/plugin.c
@@ -146,7 +146,8 @@ static const struct plugin_api rockbox_api = {
     font_get_width,
     screen_clear_area,
     gui_scrollbar_draw,
-#endif
+#endif /* HAVE_LCD_BITMAP */
+    get_codepage_name,
 
     backlight_on,
     backlight_off,
@@ -482,6 +483,7 @@ static const struct plugin_api rockbox_api = {
     &statusbars,
     gui_syncstatusbar_draw,
     /* options */
+    get_settings_list,
     find_setting,
     option_screen,
     set_option,
@@ -619,8 +621,6 @@ static const struct plugin_api rockbox_api = {
     appsversion,
     /* new stuff at the end, sort into place next time
        the API gets incompatible */
-    get_settings_list,
-    get_codepage_name,
 };
 
 int plugin_load(const char* plugin, const void* parameter)
diff --git a/apps/plugin.h b/apps/plugin.h
index fd01e15bbd..e91c866098 100644
--- a/apps/plugin.h
+++ b/apps/plugin.h
@@ -7,7 +7,7 @@
  *                     \/            \/     \/    \/            \/
  * $Id$
  *
- * Copyright (C) 2002 Björn Stenberg
+ * Copyright (C) 2002 Björn Stenberg
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -131,12 +131,12 @@ void* plugin_get_buffer(size_t *buffer_size);
 #define PLUGIN_MAGIC 0x526F634B /* RocK */
 
 /* increase this every time the api struct changes */
-#define PLUGIN_API_VERSION 128
+#define PLUGIN_API_VERSION 129
 
 /* update this to latest version if a change to the api struct breaks
    backwards compatibility (and please take the opportunity to sort in any
    new function which are "waiting" at the end of the function table) */
-#define PLUGIN_MIN_API_VERSION 127
+#define PLUGIN_MIN_API_VERSION 129
 
 /* plugin return codes */
 enum plugin_status {
@@ -244,6 +244,7 @@ struct plugin_api {
                                int min_shown, int max_shown,
                                unsigned flags);
 #endif  /* HAVE_LCD_BITMAP */
+    const char* (*get_codepage_name)(int cp);
 
     /* backlight */
     /* The backlight_* functions must be present in the API regardless whether
@@ -408,13 +409,13 @@ struct plugin_api {
     long (*default_event_handler)(long event);
     long (*default_event_handler_ex)(long event, void (*callback)(void *), void *parameter);
     struct thread_entry* threads;
-    struct thread_entry* (*create_thread)(void (*function)(void), void* stack,
-                                          size_t stack_size, unsigned flags,
-                                          const char *name
-                                          IF_PRIO(, int priority)
-                                          IF_COP(, unsigned int core));
+    unsigned int (*create_thread)(void (*function)(void), void* stack,
+                                  size_t stack_size, unsigned flags,
+                                  const char *name
+                                  IF_PRIO(, int priority)
+                                  IF_COP(, unsigned int core));
     void (*thread_exit)(void);
-    void (*thread_wait)(struct thread_entry *thread);
+    void (*thread_wait)(unsigned int thread_id);
 #if CONFIG_CODEC == SWCODEC
     void (*mutex_init)(struct mutex *m);
     void (*mutex_lock)(struct mutex *m);
@@ -456,7 +457,7 @@ struct plugin_api {
 #if CONFIG_CODEC == SWCODEC
     void (*queue_enable_queue_send)(struct event_queue *q,
                                     struct queue_sender_list *send,
-                                    struct thread_entry *owner);
+                                    unsigned int thread_id);
     bool (*queue_empty)(const struct event_queue *q);
     void (*queue_wait)(struct event_queue *q, struct queue_event *ev);
     intptr_t (*queue_send)(struct event_queue *q, long id,
@@ -616,6 +617,7 @@ struct plugin_api {
     void (*gui_syncstatusbar_draw)(struct gui_syncstatusbar * bars, bool force_redraw);
     
     /* options */
+    const struct settings_list* (*get_settings_list)(int*count);
     const struct settings_list* (*find_setting)(const void* variable, int *id);
     bool (*option_screen)(const struct settings_list *setting,
                           struct viewport parent[NB_SCREENS],
@@ -771,7 +773,7 @@ struct plugin_api {
                                   char *buf, int buflen);
 #endif
 
-    void (*thread_thaw)(struct thread_entry *thread);
+    void (*thread_thaw)(unsigned int thread_id);
  
 #ifdef HAVE_SEMAPHORE_OBJECTS
     void (*semaphore_init)(struct semaphore *s, int max, int start);
@@ -782,8 +784,6 @@ struct plugin_api {
         const char *appsversion;
     /* new stuff at the end, sort into place next time
        the API gets incompatible */
-    const struct settings_list* (*get_settings_list)(int*count);
-    const char* (*get_codepage_name)(int cp);
 };
 
 /* plugin header */
diff --git a/apps/plugins/alpine_cdc.c b/apps/plugins/alpine_cdc.c
index dfffc3b3cd..d15e26ae36 100644
--- a/apps/plugins/alpine_cdc.c
+++ b/apps/plugins/alpine_cdc.c
@@ -206,7 +206,7 @@ struct
 {
     bool foreground; /* set as long as we're owning the UI */
     bool exiting; /* signal to the thread that we want to exit */
-    struct thread_entry *thread; /* worker thread id */
+    unsigned int thread; /* worker thread id */
 } gTread;
 
 static const struct plugin_api* rb; /* here is the global API struct pointer */
diff --git a/apps/plugins/battery_bench.c b/apps/plugins/battery_bench.c
index b951b01432..0c30ebabc3 100644
--- a/apps/plugins/battery_bench.c
+++ b/apps/plugins/battery_bench.c
@@ -216,7 +216,7 @@ struct batt_info
 
 #define BUF_ELEMENTS    (sizeof(bat)/sizeof(struct batt_info))
 
-static struct thread_entry *thread_id;
+static unsigned int thread_id;
 static struct event_queue thread_q;
 static bool in_usb_mode;
 static unsigned int buf_idx;
@@ -537,7 +537,7 @@ int main(void)
     if ((thread_id = rb->create_thread(thread, thread_stack,
         sizeof(thread_stack), 0, "Battery Benchmark" 
         IF_PRIO(, PRIORITY_BACKGROUND)
-        IF_COP(, CPU))) == NULL)
+        IF_COP(, CPU))) == 0)
     {
         rb->splash(HZ, "Cannot create thread!");
         return PLUGIN_ERROR;
diff --git a/apps/plugins/mpegplayer/audio_thread.c b/apps/plugins/mpegplayer/audio_thread.c
index 45226575c9..2fb46efd56 100644
--- a/apps/plugins/mpegplayer/audio_thread.c
+++ b/apps/plugins/mpegplayer/audio_thread.c
@@ -732,7 +732,7 @@ bool audio_thread_init(void)
     rb->queue_enable_queue_send(audio_str.hdr.q, &audio_str_queue_send,
                                 audio_str.thread);
 
-    if (audio_str.thread == NULL)
+    if (audio_str.thread == 0)
         return false;
 
     /* Wait for thread to initialize */
@@ -744,11 +744,11 @@ bool audio_thread_init(void)
 /* Stops the audio thread */
 void audio_thread_exit(void)
 {
-    if (audio_str.thread != NULL)
+    if (audio_str.thread != 0)
     {
         str_post_msg(&audio_str, STREAM_QUIT, 0);
         rb->thread_wait(audio_str.thread);
-        audio_str.thread = NULL;
+        audio_str.thread = 0;
     }
 
 #ifndef SIMULATOR
diff --git a/apps/plugins/mpegplayer/disk_buf.c b/apps/plugins/mpegplayer/disk_buf.c
index df5e005b50..c008139356 100644
--- a/apps/plugins/mpegplayer/disk_buf.c
+++ b/apps/plugins/mpegplayer/disk_buf.c
@@ -835,7 +835,7 @@ void disk_buf_reply_msg(intptr_t retval)
 
 bool disk_buf_init(void)
 {
-    disk_buf.thread = NULL;
+    disk_buf.thread = 0;
     list_initialize(&nf_list);
 
     rb->mutex_init(&disk_buf_mtx);
@@ -893,7 +893,7 @@ bool disk_buf_init(void)
     rb->queue_enable_queue_send(disk_buf.q, &disk_buf_queue_send,
                                 disk_buf.thread);
 
-    if (disk_buf.thread == NULL)
+    if (disk_buf.thread == 0)
         return false;
 
     /* Wait for thread to initialize */
@@ -904,10 +904,10 @@ bool disk_buf_init(void)
 
 void disk_buf_exit(void)
 {
-    if (disk_buf.thread != NULL)
+    if (disk_buf.thread != 0)
     {
         rb->queue_post(disk_buf.q, STREAM_QUIT, 0);
         rb->thread_wait(disk_buf.thread);
-        disk_buf.thread = NULL;
+        disk_buf.thread = 0;
     }
 }
diff --git a/apps/plugins/mpegplayer/disk_buf.h b/apps/plugins/mpegplayer/disk_buf.h
index b6399c81d1..e16939a92e 100644
--- a/apps/plugins/mpegplayer/disk_buf.h
+++ b/apps/plugins/mpegplayer/disk_buf.h
@@ -62,7 +62,7 @@ struct dbuf_range
  * playback events as well as buffering */
 struct disk_buf
 {
-    struct thread_entry *thread;
+    unsigned int thread;
     struct event_queue *q;
     uint8_t *start;   /* Start pointer */
     uint8_t *end;     /* End of buffer pointer less MPEG_GUARDBUF_SIZE. The
diff --git a/apps/plugins/mpegplayer/mpeg_parser.c b/apps/plugins/mpegplayer/mpeg_parser.c
index 54a6f23d92..42c388b375 100644
--- a/apps/plugins/mpegplayer/mpeg_parser.c
+++ b/apps/plugins/mpegplayer/mpeg_parser.c
@@ -1027,7 +1027,7 @@ intptr_t parser_send_video_msg(long id, intptr_t data)
 {
     intptr_t retval = 0;
 
-    if (video_str.thread != NULL && disk_buf.in_file >= 0)
+    if (video_str.thread != 0 && disk_buf.in_file >= 0)
     {
         /* Hook certain messages since they involve multiple operations
          * behind the scenes */
diff --git a/apps/plugins/mpegplayer/stream_mgr.c b/apps/plugins/mpegplayer/stream_mgr.c
index 424d2fe503..222ffb7d6b 100644
--- a/apps/plugins/mpegplayer/stream_mgr.c
+++ b/apps/plugins/mpegplayer/stream_mgr.c
@@ -908,7 +908,7 @@ static void stream_mgr_thread(void)
 /* Opens a new file */
 int stream_open(const char *filename)
 {
-    if (stream_mgr.thread != NULL)
+    if (stream_mgr.thread != 0)
         return stream_mgr_send_msg(STREAM_OPEN, (intptr_t)filename);
     return STREAM_ERROR;
 }
@@ -916,7 +916,7 @@ int stream_open(const char *filename)
 /* Plays the current file starting at time 'start' */
 int stream_play(void)
 {
-    if (stream_mgr.thread != NULL)
+    if (stream_mgr.thread != 0)
         return stream_mgr_send_msg(STREAM_PLAY, 0);
     return STREAM_ERROR;
 }
@@ -924,7 +924,7 @@ int stream_play(void)
 /* Pauses playback if playing */
 int stream_pause(void)
 {
-    if (stream_mgr.thread != NULL)
+    if (stream_mgr.thread != 0)
         return stream_mgr_send_msg(STREAM_PAUSE, false);
     return STREAM_ERROR;
 }
@@ -932,7 +932,7 @@ int stream_pause(void)
 /* Resumes playback if paused */
 int stream_resume(void)
 {
-    if (stream_mgr.thread != NULL)
+    if (stream_mgr.thread != 0)
         return stream_mgr_send_msg(STREAM_PAUSE, true);
     return STREAM_ERROR;
 }
@@ -940,7 +940,7 @@ int stream_resume(void)
 /* Stops playback if not stopped */
 int stream_stop(void)
 {
-    if (stream_mgr.thread != NULL)
+    if (stream_mgr.thread != 0)
         return stream_mgr_send_msg(STREAM_STOP, 0);
     return STREAM_ERROR;
 }
@@ -950,7 +950,7 @@ int stream_seek(uint32_t time, int whence)
 {
     int ret;
 
-    if (stream_mgr.thread == NULL)
+    if (stream_mgr.thread == 0)
         return STREAM_ERROR;
 
     stream_mgr_lock();
@@ -968,7 +968,7 @@ int stream_seek(uint32_t time, int whence)
 /* Closes the current file */
 int stream_close(void)
 {
-    if (stream_mgr.thread != NULL)
+    if (stream_mgr.thread != 0)
         return stream_mgr_send_msg(STREAM_CLOSE, 0);
     return STREAM_ERROR;
 }
@@ -1018,7 +1018,7 @@ int stream_init(void)
     rb->queue_enable_queue_send(stream_mgr.q, &stream_mgr_queue_send,
                                 stream_mgr.thread);
 
-    if (stream_mgr.thread == NULL)
+    if (stream_mgr.thread == 0)
     {
         rb->splash(HZ, "Could not create stream manager thread!");
         return STREAM_ERROR;
@@ -1073,11 +1073,11 @@ void stream_exit(void)
     disk_buf_exit();
     pcm_output_exit();
 
-    if (stream_mgr.thread != NULL)
+    if (stream_mgr.thread != 0)
     {
         stream_mgr_post_msg(STREAM_QUIT, 0);
         rb->thread_wait(stream_mgr.thread);
-        stream_mgr.thread = NULL;
+        stream_mgr.thread = 0;
     }
 
 #ifndef HAVE_LCD_COLOR
diff --git a/apps/plugins/mpegplayer/stream_mgr.h b/apps/plugins/mpegplayer/stream_mgr.h
index e3ea9207e6..a00b39f189 100644
--- a/apps/plugins/mpegplayer/stream_mgr.h
+++ b/apps/plugins/mpegplayer/stream_mgr.h
@@ -27,7 +27,7 @@
  * coordination with assistance from the parser */
 struct stream_mgr
 {
-    struct thread_entry *thread; /* Playback control thread */
+    unsigned int thread;         /* Playback control thread */
     struct event_queue *q;       /* event queue for control thread */
     const char *filename;        /* Current filename */
     uint32_t resume_time;        /* The stream tick where playback was
diff --git a/apps/plugins/mpegplayer/stream_thread.h b/apps/plugins/mpegplayer/stream_thread.h
index d6e42d274f..30bf46e6ff 100644
--- a/apps/plugins/mpegplayer/stream_thread.h
+++ b/apps/plugins/mpegplayer/stream_thread.h
@@ -45,7 +45,7 @@ struct stream_hdr
 struct stream
 {
     struct stream_hdr hdr;       /* Base stream data */
-    struct thread_entry *thread; /* Stream's thread */
+    unsigned int thread;         /* Stream's thread */
     uint8_t* curr_packet;        /* Current stream packet beginning */
     uint8_t* curr_packet_end;    /* Current stream packet end */
     struct list_item l;          /* List of streams - either reserve pool
diff --git a/apps/plugins/mpegplayer/video_thread.c b/apps/plugins/mpegplayer/video_thread.c
index 100904b01b..8b84686a3b 100644
--- a/apps/plugins/mpegplayer/video_thread.c
+++ b/apps/plugins/mpegplayer/video_thread.c
@@ -1009,7 +1009,7 @@ bool video_thread_init(void)
     rb->queue_enable_queue_send(video_str.hdr.q, &video_str_queue_send,
                                 video_str.thread);
 
-    if (video_str.thread == NULL)
+    if (video_str.thread == 0)
         return false;
 
     /* Wait for thread to initialize */
@@ -1022,11 +1022,11 @@ bool video_thread_init(void)
 /* Terminates the video thread */
 void video_thread_exit(void)
 {
-    if (video_str.thread != NULL)
+    if (video_str.thread != 0)
     {
         str_post_msg(&video_str, STREAM_QUIT, 0);
         rb->thread_wait(video_str.thread);
         IF_COP(invalidate_icache());
-        video_str.thread = NULL;
+        video_str.thread = 0;
     }
 }
diff --git a/apps/plugins/pictureflow.c b/apps/plugins/pictureflow.c
index 29e8a749d5..232c3f6bc4 100644
--- a/apps/plugins/pictureflow.c
+++ b/apps/plugins/pictureflow.c
@@ -218,7 +218,7 @@ struct mutex slide_cache_stack_lock;
 
 static int empty_slide_hid;
 
-struct thread_entry *thread_id;
+unsigned int thread_id;
 struct event_queue thread_q;
 
 static char tmp_path_name[MAX_PATH];
@@ -831,7 +831,7 @@ bool create_pf_thread(void)
                                IF_PRIO(, PRIORITY_BACKGROUND)
                                IF_COP(, CPU)
                                       )
-        ) == NULL) {
+        ) == 0) {
         return false;
     }
     thread_is_running = true;
diff --git a/apps/plugins/test_codec.c b/apps/plugins/test_codec.c
index b1f5aff385..17effd8dfd 100644
--- a/apps/plugins/test_codec.c
+++ b/apps/plugins/test_codec.c
@@ -525,7 +525,7 @@ static enum plugin_status test_track(const char* filename)
     long ticks;
     unsigned long speed;
     unsigned long duration;
-    struct thread_entry* codecthread_id;
+    unsigned int codecthread_id;
     const char* ch;
 
     /* Display filename (excluding any path)*/
@@ -590,7 +590,7 @@ static enum plugin_status test_track(const char* filename)
 
     if ((codecthread_id = rb->create_thread(codec_thread,
             codec_stack, codec_stack_size, 0, "testcodec"
-            IF_PRIO(,PRIORITY_PLAYBACK) IF_COP(, CPU))) == NULL)
+            IF_PRIO(,PRIORITY_PLAYBACK) IF_COP(, CPU))) == 0)
     {
         log_text("Cannot create codec thread!",true);
         goto exit;
diff --git a/apps/plugins/test_sampr.c b/apps/plugins/test_sampr.c
index 77f9b8a779..1131a7a989 100644
--- a/apps/plugins/test_sampr.c
+++ b/apps/plugins/test_sampr.c
@@ -39,7 +39,7 @@ static unsigned long hw_sampr IDATA_ATTR = HW_SAMPR_DEFAULT;
 
 static int gen_thread_stack[DEFAULT_STACK_SIZE/sizeof(int)] IBSS_ATTR;
 static bool gen_quit IBSS_ATTR;
-static struct thread_entry *gen_thread_p;
+static unsigned int gen_thread_id;
 
 #define OUTPUT_CHUNK_COUNT (1 << 1)
 #define OUTPUT_CHUNK_MASK (OUTPUT_CHUNK_COUNT-1)
@@ -233,11 +233,11 @@ static void play_tone(bool volume_set)
     output_clear();
     update_gen_step();
 
-    gen_thread_p = rb->create_thread(gen_thread_func, gen_thread_stack,
-                                     sizeof(gen_thread_stack), 0,
-                                     "test_sampr generator"
-                                     IF_PRIO(, PRIORITY_PLAYBACK)
-                                     IF_COP(, CPU));
+    gen_thread_id = rb->create_thread(gen_thread_func, gen_thread_stack,
+                                      sizeof(gen_thread_stack), 0,
+                                      "test_sampr generator"
+                                      IF_PRIO(, PRIORITY_PLAYBACK)
+                                      IF_COP(, CPU));
 
     rb->pcm_play_data(get_more, NULL, 0);
 
@@ -260,7 +260,7 @@ static void play_tone(bool volume_set)
 
     gen_quit = true;
 
-    rb->thread_wait(gen_thread_p);
+    rb->thread_wait(gen_thread_id);
 
     rb->pcm_play_stop();
 
diff --git a/apps/recorder/pcm_record.c b/apps/recorder/pcm_record.c
index dbbc6901ec..9ceb68c796 100644
--- a/apps/recorder/pcm_record.c
+++ b/apps/recorder/pcm_record.c
@@ -37,7 +37,7 @@
 
 /***************************************************************************/
 
-extern struct thread_entry *codec_thread_p;
+extern uintptr_t codec_thread_id;
 
 /** General recording state **/
 static bool is_recording;              /* We are recording                 */
@@ -220,7 +220,7 @@ static struct event_queue       pcmrec_queue SHAREDBSS_ATTR;
 static struct queue_sender_list pcmrec_queue_send SHAREDBSS_ATTR;
 static long                pcmrec_stack[3*DEFAULT_STACK_SIZE/sizeof(long)];
 static const char          pcmrec_thread_name[] = "pcmrec";
-static struct thread_entry *pcmrec_thread_p;
+static unsigned int pcmrec_thread_id = 0;
 
 static void pcmrec_thread(void);
 
@@ -365,12 +365,12 @@ unsigned long pcm_rec_sample_rate(void)
 void pcm_rec_init(void)
 {
     queue_init(&pcmrec_queue, true);
-    pcmrec_thread_p =
+    pcmrec_thread_id =
         create_thread(pcmrec_thread, pcmrec_stack, sizeof(pcmrec_stack),
                       0, pcmrec_thread_name IF_PRIO(, PRIORITY_RECORDING)
                               IF_COP(, CPU));
     queue_enable_queue_send(&pcmrec_queue, &pcmrec_queue_send,
-                            pcmrec_thread_p);
+                            pcmrec_thread_id);
 } /* pcm_rec_init */
 
 /** audio_* group **/
@@ -878,10 +878,10 @@ static void pcmrec_flush(unsigned flush_num)
                priority until finished */
             logf("pcmrec: boost (%s)",
                  num >= flood_watermark ? "num" : "time");
-            prio_pcmrec = thread_set_priority(NULL,
-                                thread_get_priority(NULL) - 4);
-            prio_codec  = thread_set_priority(codec_thread_p,
-                                thread_get_priority(codec_thread_p) - 4);
+            prio_pcmrec = thread_set_priority(THREAD_ID_CURRENT,
+                                thread_get_priority(THREAD_ID_CURRENT) - 4);
+            prio_codec  = thread_set_priority(codec_thread_id,
+                                thread_get_priority(codec_thread_id) - 4);
         }
 #endif
 
@@ -931,8 +931,8 @@ static void pcmrec_flush(unsigned flush_num)
     {
         /* return to original priorities */
         logf("pcmrec: unboost priority");
-        thread_set_priority(NULL, prio_pcmrec);
-        thread_set_priority(codec_thread_p, prio_codec);
+        thread_set_priority(THREAD_ID_CURRENT, prio_pcmrec);
+        thread_set_priority(codec_thread_id, prio_codec);
     }
 
     last_flush_tick = current_tick; /* save tick when we left */
diff --git a/apps/voice_thread.c b/apps/voice_thread.c
index 084c3872c6..86e80cece3 100644
--- a/apps/voice_thread.c
+++ b/apps/voice_thread.c
@@ -54,7 +54,7 @@
 #define VOICE_SAMPLE_DEPTH   16 /* Sample depth in bits */
 
 /* Voice thread variables */
-static struct thread_entry *voice_thread_p = NULL;
+static unsigned int voice_thread_id = 0;
 static long voice_stack[0x7c0/sizeof(long)] IBSS_ATTR_VOICE_STACK;
 static const char voice_thread_name[] = "voice";
 
@@ -434,25 +434,25 @@ void voice_thread_init(void)
     queue_init(&voice_queue, false);
     mutex_init(&voice_mutex);
 
-    voice_thread_p = create_thread(voice_thread, voice_stack,
+    voice_thread_id = create_thread(voice_thread, voice_stack,
             sizeof(voice_stack), CREATE_THREAD_FROZEN,
             voice_thread_name IF_PRIO(, PRIORITY_PLAYBACK) IF_COP(, CPU));
 
     queue_enable_queue_send(&voice_queue, &voice_queue_sender_list,
-                            voice_thread_p);
+                            voice_thread_id);
 } /* voice_thread_init */
 
 /* Unfreeze the voice thread */
 void voice_thread_resume(void)
 {
     logf("Thawing voice thread");
-    thread_thaw(voice_thread_p);
+    thread_thaw(voice_thread_id);
 }
 
 #ifdef HAVE_PRIORITY_SCHEDULING
 /* Set the voice thread priority */
 void voice_thread_set_priority(int priority)
 {
-    thread_set_priority(voice_thread_p, priority);
+    thread_set_priority(voice_thread_id, priority);
 }
 #endif
diff --git a/firmware/backlight.c b/firmware/backlight.c
index 07cc9532be..66cc6df569 100644
--- a/firmware/backlight.c
+++ b/firmware/backlight.c
@@ -130,7 +130,7 @@ static long backlight_stack[DEFAULT_STACK_SIZE/sizeof(long)];
 static const char backlight_thread_name[] = "backlight";
 static struct event_queue backlight_queue;
 #ifdef BACKLIGHT_DRIVER_CLOSE
-static struct thread_entry *backlight_thread_p = NULL;
+static unsigned int backlight_thread_id = 0;
 #endif
 
 static int backlight_timer SHAREDBSS_ATTR;
@@ -744,7 +744,7 @@ void backlight_init(void)
      * call the appropriate backlight_set_*() functions, only changing light
      * status if necessary. */
 #ifdef BACKLIGHT_DRIVER_CLOSE
-    backlight_thread_p =
+    backlight_thread_id =
 #endif
     create_thread(backlight_thread, backlight_stack,
                   sizeof(backlight_stack), 0, backlight_thread_name
@@ -756,13 +756,13 @@ void backlight_init(void)
 #ifdef BACKLIGHT_DRIVER_CLOSE
 void backlight_close(void)
 {
-    struct thread_entry *thread = backlight_thread_p;
+    unsigned int thread = backlight_thread_id;
 
     /* Wait for thread to exit */
-    if (thread == NULL)
+    if (thread == 0)
         return;
 
-    backlight_thread_p = NULL;
+    backlight_thread_id = 0;
 
     queue_post(&backlight_queue, BACKLIGHT_QUIT, 0);
     thread_wait(thread);
diff --git a/firmware/drivers/ata.c b/firmware/drivers/ata.c
index 00a7c3e19a..e3fa3e8958 100644
--- a/firmware/drivers/ata.c
+++ b/firmware/drivers/ata.c
@@ -71,7 +71,7 @@
 #endif
 
 #ifdef ATA_DRIVER_CLOSE
-static struct thread_entry *ata_thread_p = NULL;
+static unsigned int ata_thread_id = 0;
 #endif
 
 #if defined(MAX_PHYS_SECTOR_SIZE) && MEM == 64
@@ -94,7 +94,8 @@ static void ata_lock_init(struct ata_lock *l)
 
 static void ata_lock_lock(struct ata_lock *l)
 {
-    struct thread_entry * const current = thread_get_current();
+    struct thread_entry * const current =
+        thread_id_entry(THREAD_ID_CURRENT);
 
     if (current == l->thread)
     {
@@ -1350,7 +1351,7 @@ int ata_init(void)
 
         last_disk_activity = current_tick;
 #ifdef ATA_DRIVER_CLOSE
-        ata_thread_p =
+        ata_thread_id =
 #endif
         create_thread(ata_thread, ata_stack,
                       sizeof(ata_stack), 0, ata_thread_name
@@ -1370,15 +1371,15 @@ int ata_init(void)
 #ifdef ATA_DRIVER_CLOSE
 void ata_close(void)
 {
-    struct thread_entry *thread = ata_thread_p;
+    unsigned int thread_id = ata_thread_id;
     
-    if (thread == NULL)
+    if (thread_id == 0)
         return;
 
-    ata_thread_p = NULL;
+    ata_thread_id = 0;
 
     queue_post(&ata_queue, Q_CLOSE, 0);
-    thread_wait(thread);
+    thread_wait(thread_id);
 }
 #endif /* ATA_DRIVER_CLOSE */
 
diff --git a/firmware/export/kernel.h b/firmware/export/kernel.h
index beba58eb21..ef65463e5d 100644
--- a/firmware/export/kernel.h
+++ b/firmware/export/kernel.h
@@ -261,7 +261,7 @@ extern void queue_post(struct event_queue *q, long id, intptr_t data);
 #ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
 extern void queue_enable_queue_send(struct event_queue *q,
                                     struct queue_sender_list *send,
-                                    struct thread_entry *owner);
+                                    unsigned int owner_id);
 extern intptr_t queue_send(struct event_queue *q, long id, intptr_t data);
 extern void queue_reply(struct event_queue *q, intptr_t retval);
 extern bool queue_in_queue_send(struct event_queue *q);
diff --git a/firmware/export/thread.h b/firmware/export/thread.h
index c4dfbf4ed3..4c1e952347 100644
--- a/firmware/export/thread.h
+++ b/firmware/export/thread.h
@@ -58,9 +58,6 @@
 #define NUM_PRIORITIES           32
 #define PRIORITY_IDLE            32  /* Priority representative of no tasks */
 
-/* TODO: Only a minor tweak to create_thread would be needed to let
- * thread slots be caller allocated - no essential threading functionality
- * depends upon an array */
 #if CONFIG_CODEC == SWCODEC
 
 #ifdef HAVE_RECORDING
@@ -280,6 +277,7 @@ struct thread_entry
     int skip_count;            /* Number of times skipped if higher priority
                                   thread was running */
 #endif
+    uint16_t id;               /* Current slot id */
     unsigned short stack_size; /* Size of stack in bytes */
 #ifdef HAVE_PRIORITY_SCHEDULING
     unsigned char base_priority; /* Base priority (set explicitly during
@@ -298,6 +296,16 @@ struct thread_entry
 #endif
 };
 
+/*** Macros for internal use ***/
+/* Thread ID, 16 bits = |VVVVVVVV|SSSSSSSS| */
+#define THREAD_ID_VERSION_SHIFT      8
+#define THREAD_ID_VERSION_MASK  0xff00
+#define THREAD_ID_SLOT_MASK     0x00ff
+#define THREAD_ID_INIT(n)       ((1u << THREAD_ID_VERSION_SHIFT) | (n))
+
+/* Specify current thread in a function taking an ID. */
+#define THREAD_ID_CURRENT ((unsigned int)-1)
+
 #if NUM_CORES > 1
 /* Operations to be performed just before stopping a thread and starting
    a new one if specified before calling switch_thread */
@@ -475,11 +483,11 @@ void init_threads(void);
 
 /* Allocate a thread in the scheduler */
 #define CREATE_THREAD_FROZEN   0x00000001 /* Thread is frozen at create time */
-struct thread_entry*
-    create_thread(void (*function)(void), void* stack, size_t stack_size,
-                  unsigned flags, const char *name
-                  IF_PRIO(, int priority)
-                          IF_COP(, unsigned int core));
+unsigned int create_thread(void (*function)(void),
+                           void* stack, size_t stack_size,
+                           unsigned flags, const char *name
+                           IF_PRIO(, int priority)
+                           IF_COP(, unsigned int core));
 
 /* Set and clear the CPU frequency boost flag for the calling thread */
 #ifdef HAVE_SCHEDULER_BOOSTCTRL
@@ -489,17 +497,19 @@ void cancel_cpu_boost(void);
 #define trigger_cpu_boost()
 #define cancel_cpu_boost()
 #endif
+/* Return thread entry from id */
+struct thread_entry *thread_id_entry(unsigned int thread_id);
 /* Make a frozed thread runnable (when started with CREATE_THREAD_FROZEN).
  * Has no effect on a thread not frozen. */
-void thread_thaw(struct thread_entry *thread);
+void thread_thaw(unsigned int thread_id);
 /* Wait for a thread to exit */
-void thread_wait(struct thread_entry *thread);
+void thread_wait(unsigned int thread_id);
 /* Exit the current thread */
 void thread_exit(void);
 #if defined(DEBUG) || defined(ROCKBOX_HAS_LOGF)
 #define ALLOW_REMOVE_THREAD
 /* Remove a thread from the scheduler */
-void remove_thread(struct thread_entry *thread);
+void remove_thread(unsigned int thread_id);
 #endif
 
 /* Switch to next runnable thread */
@@ -526,13 +536,13 @@ unsigned int thread_queue_wake(struct thread_entry **list);
 unsigned int wakeup_thread(struct thread_entry **list);
 
 #ifdef HAVE_PRIORITY_SCHEDULING
-int thread_set_priority(struct thread_entry *thread, int priority);
-int thread_get_priority(struct thread_entry *thread);
+int thread_set_priority(unsigned int thread_id, int priority);
+int thread_get_priority(unsigned int thread_id);
 #endif /* HAVE_PRIORITY_SCHEDULING */
 #if NUM_CORES > 1
 unsigned int switch_core(unsigned int new_core);
 #endif
-struct thread_entry * thread_get_current(void);
+unsigned int thread_get_current(void);
 
 /* Debugging info - only! */
 int thread_stack_usage(const struct thread_entry *thread);
diff --git a/firmware/kernel.c b/firmware/kernel.c
index 920893818a..553f6721a1 100644
--- a/firmware/kernel.c
+++ b/firmware/kernel.c
@@ -352,11 +352,12 @@ static void queue_remove_sender_thread_cb(struct thread_entry *thread)
  * specified for priority inheritance to operate.
  *
  * Use of queue_wait(_w_tmo) by multiple threads on a queue using synchronous
- * messages results in an undefined order of message replies.
+ * messages results in an undefined order of message replies or possible default
+ * replies if two or more waits happen before a reply is done.
  */
 void queue_enable_queue_send(struct event_queue *q,
                              struct queue_sender_list *send,
-                             struct thread_entry *owner)
+                             unsigned int owner_id)
 {
     int oldlevel = disable_irq_save();
     corelock_lock(&q->cl);
@@ -367,9 +368,11 @@ void queue_enable_queue_send(struct event_queue *q,
 #ifdef HAVE_PRIORITY_SCHEDULING
         send->blocker.wakeup_protocol = wakeup_priority_protocol_release;
         send->blocker.priority = PRIORITY_IDLE;
-        send->blocker.thread = owner;
-        if(owner != NULL)
+        if(owner_id != 0)
+        {
+            send->blocker.thread = thread_id_entry(owner_id);
             q->blocker_p = &send->blocker;
+        }
 #endif
         q->send = send;
     }
@@ -377,7 +380,7 @@ void queue_enable_queue_send(struct event_queue *q,
     corelock_unlock(&q->cl);
     restore_irq(oldlevel);
 
-    (void)owner;
+    (void)owner_id;
 }
 
 /* Unblock a blocked thread at a given event index */
@@ -532,7 +535,7 @@ void queue_wait(struct event_queue *q, struct queue_event *ev)
 
 #ifdef HAVE_PRIORITY_SCHEDULING
     KERNEL_ASSERT(QUEUE_GET_THREAD(q) == NULL ||
-                  QUEUE_GET_THREAD(q) == thread_get_current(),
+                  QUEUE_GET_THREAD(q) == cores[CURRENT_CORE].running,
                   "queue_wait->wrong thread\n");
 #endif
 
@@ -579,7 +582,7 @@ void queue_wait_w_tmo(struct event_queue *q, struct queue_event *ev, int ticks)
 
 #ifdef HAVE_EXTENDED_MESSAGING_AND_NAME
     KERNEL_ASSERT(QUEUE_GET_THREAD(q) == NULL ||
-                  QUEUE_GET_THREAD(q) == thread_get_current(),
+                  QUEUE_GET_THREAD(q) == cores[CURRENT_CORE].running,
                   "queue_wait_w_tmo->wrong thread\n");
 #endif
 
@@ -914,10 +917,10 @@ void mutex_lock(struct mutex *m)
 void mutex_unlock(struct mutex *m)
 {
     /* unlocker not being the owner is an unlocking violation */
-    KERNEL_ASSERT(MUTEX_GET_THREAD(m) == thread_get_current(),
+    KERNEL_ASSERT(MUTEX_GET_THREAD(m) == cores[CURRENT_CORE].running,
                   "mutex_unlock->wrong thread (%s != %s)\n",
                   MUTEX_GET_THREAD(m)->name,
-                  thread_get_current()->name);
+                  cores[CURRENT_CORE].running->name);
 
     if(m->count > 0)
     {
@@ -990,7 +993,7 @@ void spinlock_lock(struct spinlock *l)
 void spinlock_unlock(struct spinlock *l)
 {
     /* unlocker not being the owner is an unlocking violation */
-    KERNEL_ASSERT(l->thread == thread_get_current(),
+    KERNEL_ASSERT(l->thread == cores[CURRENT_CORE].running,
                   "spinlock_unlock->wrong thread\n");
 
     if(l->count > 0)
diff --git a/firmware/target/arm/imx31/gigabeat-s/mc13783-imx31.c b/firmware/target/arm/imx31/gigabeat-s/mc13783-imx31.c
index c185994bfc..81849d0852 100644
--- a/firmware/target/arm/imx31/gigabeat-s/mc13783-imx31.c
+++ b/firmware/target/arm/imx31/gigabeat-s/mc13783-imx31.c
@@ -69,7 +69,7 @@ static const unsigned char pmic_ints_regs[2] =
 
 #ifdef PMIC_DRIVER_CLOSE
 static bool pmic_close = false;
-static struct thread_entry *mc13783_thread_p = NULL;
+static unsigned int mc13783_thread_id = 0;
 #endif
 
 static void mc13783_interrupt_thread(void)
@@ -149,7 +149,7 @@ void mc13783_init(void)
     MC13783_GPIO_ISR = (1ul << MC13783_GPIO_LINE);
 
 #ifdef PMIC_DRIVER_CLOSE
-    mc13783_thread_p =
+    mc13783_thread_id =
 #endif
         create_thread(mc13783_interrupt_thread,
             mc13783_thread_stack, sizeof(mc13783_thread_stack), 0,
@@ -159,16 +159,16 @@ void mc13783_init(void)
 #ifdef PMIC_DRIVER_CLOSE
 void mc13783_close(void)
 {
-    struct thread_entry *thread = mc13783_thread_p;
+    unsigned int thread_id = mc13783_thread_p;
 
-    if (thread == NULL)
+    if (thread_id == 0)
         return;
 
-    mc13783_thread_p = NULL;
+    mc13783_thread_id = 0;
 
     pmic_close = true;
     wakeup_signal(&mc13783_wake);
-    thread_wait(thread);
+    thread_wait(thread_id);
 }
 #endif /* PMIC_DRIVER_CLOSE */
 
diff --git a/firmware/thread.c b/firmware/thread.c
index c500fc4818..377c3355b4 100644
--- a/firmware/thread.c
+++ b/firmware/thread.c
@@ -1691,8 +1691,8 @@ struct thread_entry *
     struct thread_entry *next;
     int bl_pr;
 
-    THREAD_ASSERT(thread_get_current() == bl_t,
-                  "UPPT->wrong thread", thread_get_current());
+    THREAD_ASSERT(cores[CURRENT_CORE].running == bl_t,
+                  "UPPT->wrong thread", cores[CURRENT_CORE].running);
 
     LOCK_THREAD(bl_t);
 
@@ -2031,7 +2031,7 @@ void switch_thread(void)
     }
 
 #ifdef RB_PROFILE
-    profile_thread_stopped(thread - threads);
+    profile_thread_stopped(thread->id & THREAD_ID_SLOT_MASK);
 #endif
 
     /* Begin task switching by saving our current context so that we can
@@ -2136,7 +2136,7 @@ void switch_thread(void)
     load_context(&thread->context);
 
 #ifdef RB_PROFILE
-    profile_thread_started(thread - threads);
+    profile_thread_started(thread->id & THREAD_ID_SLOT_MASK);
 #endif
 
 }
@@ -2316,6 +2316,24 @@ unsigned int thread_queue_wake(struct thread_entry **list)
 }
 
 /*---------------------------------------------------------------------------
+ * Assign the thread slot a new ID. Version is 1-255.
+ *---------------------------------------------------------------------------
+ */
+static void new_thread_id(unsigned int slot_num,
+                          struct thread_entry *thread)
+{
+    unsigned int version =
+        (thread->id + (1u << THREAD_ID_VERSION_SHIFT))
+                & THREAD_ID_VERSION_MASK;
+
+    /* If wrapped to 0, make it 1 */
+    if (version == 0)
+        version = 1u << THREAD_ID_VERSION_SHIFT;
+
+    thread->id = version | (slot_num & THREAD_ID_SLOT_MASK);
+}
+
+/*---------------------------------------------------------------------------
  * Find an empty thread slot or MAXTHREADS if none found. The slot returned
  * will be locked on multicore.
  *---------------------------------------------------------------------------
@@ -2349,6 +2367,17 @@ static struct thread_entry * find_empty_thread_slot(void)
     return thread;
 }
 
+/*---------------------------------------------------------------------------
+ * Return the thread_entry pointer for a thread_id. Return the current
+ * thread if the ID is 0 (alias for current).
+ *---------------------------------------------------------------------------
+ */
+struct thread_entry * thread_id_entry(unsigned int thread_id)
+{
+    return (thread_id == THREAD_ID_CURRENT) ?
+        cores[CURRENT_CORE].running :
+        &threads[thread_id & THREAD_ID_SLOT_MASK];
+}
 
 /*---------------------------------------------------------------------------
  * Place the current core in idle mode - woken up on interrupt or wake
@@ -2369,11 +2398,11 @@ void core_idle(void)
  * Return ID if context area could be allocated, else NULL.
  *---------------------------------------------------------------------------
  */
-struct thread_entry* 
-    create_thread(void (*function)(void), void* stack, size_t stack_size,
-                  unsigned flags, const char *name
-                  IF_PRIO(, int priority)
-                  IF_COP(, unsigned int core))
+unsigned int create_thread(void (*function)(void),
+                           void* stack, size_t stack_size,
+                           unsigned flags, const char *name
+                           IF_PRIO(, int priority)
+                           IF_COP(, unsigned int core))
 {
     unsigned int i;
     unsigned int stack_words;
@@ -2385,7 +2414,7 @@ struct thread_entry*
     thread = find_empty_thread_slot();
     if (thread == NULL)
     {
-        return NULL;
+        return 0;
     }
 
     oldlevel = disable_irq_save();
@@ -2443,15 +2472,15 @@ struct thread_entry*
     THREAD_STARTUP_INIT(core, thread, function);
 
     thread->state = state;
+    i = thread->id; /* Snapshot while locked */
 
     if (state == STATE_RUNNING)
         core_schedule_wakeup(thread);
 
     UNLOCK_THREAD(thread);
-
     restore_irq(oldlevel);
 
-    return thread;
+    return i;
 }
 
 #ifdef HAVE_SCHEDULER_BOOSTCTRL
@@ -2489,18 +2518,17 @@ void cancel_cpu_boost(void)
  * Parameter is the ID as returned from create_thread().
  *---------------------------------------------------------------------------
  */
-void thread_wait(struct thread_entry *thread)
+void thread_wait(unsigned int thread_id)
 {
     struct thread_entry *current = cores[CURRENT_CORE].running;
-
-    if (thread == NULL)
-        thread = current;
+    struct thread_entry *thread = thread_id_entry(thread_id);
 
     /* Lock thread-as-waitable-object lock */
     corelock_lock(&thread->waiter_cl);
 
     /* Be sure it hasn't been killed yet */
-    if (thread->state != STATE_KILLED)
+    if (thread_id == THREAD_ID_CURRENT ||
+        (thread->id == thread_id && thread->state != STATE_KILLED))
     {
         IF_COP( current->obj_cl = &thread->waiter_cl; )
         current->bqp = &thread->queue;
@@ -2538,9 +2566,10 @@ void thread_exit(void)
     if (current->name == THREAD_DESTRUCT)
     {
         /* Thread being killed - become a waiter */
+        unsigned int id = current->id;
         UNLOCK_THREAD(current);
         corelock_unlock(&current->waiter_cl);
-        thread_wait(current);
+        thread_wait(id);
         THREAD_PANICF("thread_exit->WK:*R", current);
     }
 #endif
@@ -2568,7 +2597,13 @@ void thread_exit(void)
     }
 
     flush_icache();
+
+    /* At this point, this thread isn't using resources allocated for
+     * execution except the slot itself. */
 #endif
+
+    /* Update ID for this slot */
+    new_thread_id(current->id, current);
     current->name = NULL;
 
     /* Signal this thread */
@@ -2593,7 +2628,7 @@ void thread_exit(void)
  * leave various objects in an undefined state.
  *---------------------------------------------------------------------------
  */
-void remove_thread(struct thread_entry *thread)
+void remove_thread(unsigned int thread_id)
 {
 #if NUM_CORES > 1
     /* core is not constant here because of core switching */
@@ -2604,13 +2639,11 @@ void remove_thread(struct thread_entry *thread)
     const unsigned int core = CURRENT_CORE;
 #endif
     struct thread_entry *current = cores[core].running;
+    struct thread_entry *thread = thread_id_entry(thread_id);
 
     unsigned state;
     int oldlevel;
 
-    if (thread == NULL)
-        thread = current;
-
     if (thread == current)
         thread_exit(); /* Current thread - do normal exit */
 
@@ -2621,10 +2654,8 @@ void remove_thread(struct thread_entry *thread)
 
     state = thread->state;
 
-    if (state == STATE_KILLED)
-    {
+    if (thread->id != thread_id || state == STATE_KILLED)
         goto thread_killed;
-    }
 
 #if NUM_CORES > 1
     if (thread->name == THREAD_DESTRUCT)
@@ -2633,7 +2664,7 @@ void remove_thread(struct thread_entry *thread)
         UNLOCK_THREAD(thread);
         corelock_unlock(&thread->waiter_cl);
         restore_irq(oldlevel);
-        thread_wait(thread);
+        thread_wait(thread_id);
         return;
     }
 
@@ -2741,6 +2772,7 @@ IF_COP( retry_state: )
     /* Otherwise thread is frozen and hasn't run yet */
     }
 
+    new_thread_id(thread_id, thread);
     thread->state = STATE_KILLED;
 
     /* If thread was waiting on itself, it will have been removed above.
@@ -2773,17 +2805,15 @@ thread_killed: /* Thread was already killed */
  * needed inheritance changes also may happen.
  *---------------------------------------------------------------------------
  */
-int thread_set_priority(struct thread_entry *thread, int priority)
+int thread_set_priority(unsigned int thread_id, int priority)
 {
     int old_base_priority = -1;
+    struct thread_entry *thread = thread_id_entry(thread_id);
 
     /* A little safety measure */
     if (priority < HIGHEST_PRIORITY || priority > LOWEST_PRIORITY)
         return -1;
 
-    if (thread == NULL)
-        thread = cores[CURRENT_CORE].running;
-
     /* Thread could be on any list and therefore on an interrupt accessible
        one - disable interrupts */
     int oldlevel = disable_irq_save();
@@ -2791,7 +2821,8 @@ int thread_set_priority(struct thread_entry *thread, int priority)
     LOCK_THREAD(thread);
 
     /* Make sure it's not killed */
-    if (thread->state != STATE_KILLED)
+    if (thread_id == THREAD_ID_CURRENT ||
+        (thread->id == thread_id && thread->state != STATE_KILLED))
     {
         int old_priority = thread->priority;
 
@@ -2908,13 +2939,19 @@ int thread_set_priority(struct thread_entry *thread, int priority)
  * Returns the current base priority for a thread.
  *---------------------------------------------------------------------------
  */
-int thread_get_priority(struct thread_entry *thread)
+int thread_get_priority(unsigned int thread_id)
 {
-    /* Simple, quick probe. */
-    if (thread == NULL)
-        thread = cores[CURRENT_CORE].running;
+    struct thread_entry *thread = thread_id_entry(thread_id);
+    int base_priority = thread->base_priority;
 
-    return thread->base_priority;
+    /* Simply check without locking slot. It may or may not be valid by the
+     * time the function returns anyway. If all tests pass, it is the
+     * correct value for when it was valid. */
+    if (thread_id != THREAD_ID_CURRENT &&
+        (thread->id != thread_id || thread->state == STATE_KILLED))
+        base_priority = -1;
+
+    return base_priority;
 }
 #endif /* HAVE_PRIORITY_SCHEDULING */
 
@@ -2924,12 +2961,16 @@ int thread_get_priority(struct thread_entry *thread)
  * virtue of the slot having a state of STATE_FROZEN.
  *---------------------------------------------------------------------------
  */
-void thread_thaw(struct thread_entry *thread)
+void thread_thaw(unsigned int thread_id)
 {
+    struct thread_entry *thread = thread_id_entry(thread_id);
     int oldlevel = disable_irq_save();
+
     LOCK_THREAD(thread);
 
-    if (thread->state == STATE_FROZEN)
+    /* If thread is the current one, it cannot be frozen, therefore
+     * there is no need to check that. */
+    if (thread->id == thread_id && thread->state == STATE_FROZEN)
         core_schedule_wakeup(thread);
 
     UNLOCK_THREAD(thread);
@@ -2940,9 +2981,9 @@ void thread_thaw(struct thread_entry *thread)
  * Return the ID of the currently executing thread.
  *---------------------------------------------------------------------------
  */
-struct thread_entry * thread_get_current(void)
+unsigned int thread_get_current(void)
 {
-    return cores[CURRENT_CORE].running;
+    return cores[CURRENT_CORE].running->id;
 }
 
 #if NUM_CORES > 1
@@ -2967,9 +3008,10 @@ unsigned int switch_core(unsigned int new_core)
     if (current->name == THREAD_DESTRUCT)
     {
         /* Thread being killed - deactivate and let process complete */
+        unsigned int id = current->id;
         UNLOCK_THREAD(current);
         restore_irq(oldlevel);
-        thread_wait(current);
+        thread_wait(id);
         /* Should never be reached */
         THREAD_PANICF("switch_core->D:*R", current);
     }
@@ -3034,6 +3076,19 @@ void init_threads(void)
     const unsigned int core = CURRENT_CORE;
     struct thread_entry *thread;
 
+    if (core == CPU)
+    {
+        /* Initialize core locks and IDs in all slots */
+        int n;
+        for (n = 0; n < MAXTHREADS; n++)
+        {
+            thread = &threads[n];
+            corelock_init(&thread->waiter_cl);
+            corelock_init(&thread->slot_cl);
+            thread->id = THREAD_ID_INIT(n);
+        }
+    }
+
     /* CPU will initialize first and then sleep */
     thread = find_empty_thread_slot();
 
@@ -3060,8 +3115,6 @@ void init_threads(void)
     thread->priority = PRIORITY_USER_INTERFACE;
     rtr_add_entry(core, PRIORITY_USER_INTERFACE);
 #endif
-    corelock_init(&thread->waiter_cl);
-    corelock_init(&thread->slot_cl);
 
     add_to_list_l(&cores[core].running, thread);
 
@@ -3070,6 +3123,7 @@ void init_threads(void)
         thread->stack = stackbegin;
         thread->stack_size = (uintptr_t)stackend - (uintptr_t)stackbegin;
 #if NUM_CORES > 1  /* This code path will not be run on single core targets */
+        /* Initialize all locking for the slots */
         /* Wait for other processors to finish their inits since create_thread
          * isn't safe to call until the kernel inits are done. The first
          * threads created in the system must of course be created by CPU. */
diff --git a/firmware/usb.c b/firmware/usb.c
index f9bfbc4dbf..2bff53e5d6 100644
--- a/firmware/usb.c
+++ b/firmware/usb.c
@@ -78,7 +78,7 @@ static int usb_mmc_countdown = 0;
 #ifdef USB_FULL_INIT
 static long usb_stack[(DEFAULT_STACK_SIZE + 0x800)/sizeof(long)];
 static const char usb_thread_name[] = "usb";
-static struct thread_entry *usb_thread_entry;
+static unsigned int usb_thread_entry = 0;
 #endif
 static struct event_queue usb_queue;
 static int last_usb_status;
@@ -539,10 +539,10 @@ void usb_start_monitoring(void)
 #ifdef USB_DRIVER_CLOSE
 void usb_close(void)
 {
-    struct thread_entry *thread = usb_thread_entry;
-    usb_thread_entry = NULL;
+    uintptr_t thread = usb_thread_entry;
+    usb_thread_entry = 0;
 
-    if (thread == NULL)
+    if (thread == 0)
         return;
 
     tick_remove_task(usb_tick);
diff --git a/uisimulator/sdl/thread-sdl.c b/uisimulator/sdl/thread-sdl.c
index 905a017ee0..ab1086dd7d 100644
--- a/uisimulator/sdl/thread-sdl.c
+++ b/uisimulator/sdl/thread-sdl.c
@@ -93,6 +93,38 @@ void thread_sdl_shutdown(void)
     SDL_DestroyMutex(m);
 }
 
+static void new_thread_id(unsigned int slot_num,
+                          struct thread_entry *thread)
+{
+    unsigned int version =
+        (thread->id + (1u << THREAD_ID_VERSION_SHIFT))
+            & THREAD_ID_VERSION_MASK;
+
+    if (version == 0)
+        version = 1u << THREAD_ID_VERSION_SHIFT;
+
+    thread->id = version | (slot_num & THREAD_ID_SLOT_MASK);
+}
+
+static struct thread_entry * find_empty_thread_slot(void)
+{
+    struct thread_entry *thread = NULL;
+    int n;
+
+    for (n = 0; n < MAXTHREADS; n++)
+    {
+        int state = threads[n].state;
+
+        if (state == STATE_KILLED)
+        {
+            thread = &threads[n];
+            break;
+        }
+    }
+
+    return thread;
+}
+
 /* Do main thread creation in this file scope to avoid the need to double-
    return to a prior call-level which would be unaware of the fact setjmp
    was used */
@@ -119,6 +151,8 @@ static int thread_sdl_app_main(void *param)
 bool thread_sdl_init(void *param)
 {
     struct thread_entry *thread;
+    int n;
+
     memset(cores, 0, sizeof(cores));
     memset(threads, 0, sizeof(threads));
 
@@ -130,6 +164,10 @@ bool thread_sdl_init(void *param)
         return false;
     }
 
+    /* Initialize all IDs */
+    for (n = 0; n < MAXTHREADS; n++)
+        threads[n].id = THREAD_ID_INIT(n);
+
     /* Slot 0 is reserved for the main thread - initialize it here and
        then create the SDL thread - it is possible to have a quick, early
        shutdown try to access the structure. */
@@ -179,23 +217,11 @@ void * thread_sdl_thread_unlock(void)
     return current;
 }
 
-static struct thread_entry * find_empty_thread_slot(void)
+struct thread_entry * thread_id_entry(unsigned int thread_id)
 {
-    struct thread_entry *thread = NULL;
-    int n;
-
-    for (n = 0; n < MAXTHREADS; n++)
-    {
-        int state = threads[n].state;
-
-        if (state == STATE_KILLED)
-        {
-            thread = &threads[n];
-            break;
-        }
-    }
-
-    return thread;
+    return (thread_id == THREAD_ID_CURRENT) ? 
+        cores[CURRENT_CORE].running :
+        &threads[thread_id & THREAD_ID_SLOT_MASK];
 }
 
 static void add_to_list_l(struct thread_entry **list,
@@ -239,9 +265,9 @@ static void remove_from_list_l(struct thread_entry **list,
     thread->l.next->l.prev = thread->l.prev;
 }
 
-struct thread_entry *thread_get_current(void)
+unsigned int thread_get_current(void)
 {
-    return cores[CURRENT_CORE].running;
+    return cores[CURRENT_CORE].running->id;
 }
 
 void switch_thread(void)
@@ -389,9 +415,11 @@ unsigned int thread_queue_wake(struct thread_entry **list)
     return result;
 }
 
-void thread_thaw(struct thread_entry *thread)
+void thread_thaw(unsigned int thread_id)
 {
-    if (thread->state == STATE_FROZEN)
+    struct thread_entry *thread = thread_id_entry(thread_id);
+
+    if (thread->id == thread_id && thread->state == STATE_FROZEN)
     {
         thread->state = STATE_RUNNING;
         SDL_SemPost(thread->context.s);
@@ -441,9 +469,9 @@ int runthread(void *data)
     return 0;
 }
 
-struct thread_entry* 
-    create_thread(void (*function)(void), void* stack, size_t stack_size,
-                  unsigned flags, const char *name)
+unsigned int create_thread(void (*function)(void),
+                           void* stack, size_t stack_size,
+                           unsigned flags, const char *name)
 {
     struct thread_entry *thread;
     SDL_Thread* t;
@@ -455,14 +483,14 @@ struct thread_entry*
     if (thread == NULL)
     {
         DEBUGF("Failed to find thread slot\n");
-        return NULL;
+        return 0;
     }
 
     s = SDL_CreateSemaphore(0);
     if (s == NULL)
     {
         DEBUGF("Failed to create semaphore\n");
-        return NULL;
+        return 0;
     }
 
     t = SDL_CreateThread(runthread, thread);
@@ -470,7 +498,7 @@ struct thread_entry*
     {
         DEBUGF("Failed to create SDL thread\n");
         SDL_DestroySemaphore(s);
-        return NULL;
+        return 0;
     }
 
     thread->stack = stack;
@@ -485,7 +513,7 @@ struct thread_entry*
     THREAD_SDL_DEBUGF("New Thread: %d (%s)\n",
                       thread - threads, THREAD_SDL_GET_NAME(thread));
 
-    return thread;
+    return thread->id;
 }
 
 void init_threads(void)
@@ -501,18 +529,22 @@ void init_threads(void)
             0, THREAD_SDL_GET_NAME(&threads[0]));
 }
 
-void remove_thread(struct thread_entry *thread)
+#ifndef ALLOW_REMOVE_THREAD
+static void remove_thread(unsigned int thread_id)
+#else
+void remove_thread(unsigned int thread_id)
+#endif
 {
     struct thread_entry *current = cores[CURRENT_CORE].running;
+    struct thread_entry *thread = thread_id_entry(thread_id);
+
     SDL_Thread *t;
     SDL_sem *s;
 
-    int oldlevel = disable_irq_save();
+    if (thread_id != THREAD_ID_CURRENT && thread->id != thread_id)
+        return;
 
-    if (thread == NULL)
-    {
-        thread = current;
-    }
+    int oldlevel = disable_irq_save();
 
     t = thread->context.t;
     s = thread->context.s;
@@ -540,6 +572,7 @@ void remove_thread(struct thread_entry *thread)
     THREAD_SDL_DEBUGF("Removing thread: %d (%s)\n",
         thread - threads, THREAD_SDL_GET_NAME(thread));
 
+    new_thread_id(thread->id, thread);
     thread->state = STATE_KILLED;
     thread_queue_wake(&thread->queue);
 
@@ -559,17 +592,16 @@ void remove_thread(struct thread_entry *thread)
 
 void thread_exit(void)
 {
-    remove_thread(NULL);
+    remove_thread(THREAD_ID_CURRENT);
 }
 
-void thread_wait(struct thread_entry *thread)
+void thread_wait(unsigned int thread_id)
 {
     struct thread_entry *current = cores[CURRENT_CORE].running;
+    struct thread_entry *thread = thread_id_entry(thread_id);
 
-    if (thread == NULL)
-        thread = current;
-
-    if (thread->state != STATE_KILLED)
+    if (thread_id == THREAD_ID_CURRENT ||
+        (thread->id == thread_id && thread->state != STATE_KILLED))
     {
         current->bqp = &thread->queue;
         block_thread(current);
@@ -583,11 +615,6 @@ int thread_stack_usage(const struct thread_entry *thread)
     (void)thread;
 }
 
-unsigned thread_get_status(const struct thread_entry *thread)
-{
-    return thread->state;
-}
-
 /* Return name if one or ID if none */
 void thread_get_name(char *buffer, int size,
                      struct thread_entry *thread)