2 files changed, 37 insertions, 5 deletions

diff --git a/firmware/export/font.h b/firmware/export/font.h
index 36c6e0a291..02476c17ff 100644
--- a/firmware/export/font.h
+++ b/firmware/export/font.h
@@ -100,6 +100,8 @@ struct font {
     
     /* file, buffer and cache management */
     int          fd;              /* fd for the font file. >= 0 if cached */
+    int          fd_width;        /* fd for the font file. >= 0 if cached */
+    int          fd_offset;       /* fd for the font file. >= 0 if cached */    
     unsigned char *buffer_start;    /* buffer to store the font in */       
     unsigned char *buffer_position; /* position in the buffer */    
     unsigned char *buffer_end;      /* end of the buffer */
diff --git a/firmware/font.c b/firmware/font.c
index 8b70a7dcb9..943f2e2d06 100644
--- a/firmware/font.c
+++ b/firmware/font.c
@@ -394,7 +394,22 @@ static bool internal_load_font(int font_id, const char *path, char *buf,
             return false;
         }
 
+        /* Cheat to get sector cache for different parts of font       *
+         * file while preloading glyphs. Without this the disk head    *
+         * thrashes between the width, offset, and bitmap data         *
+         * in glyph_cache_load().                                      */         
+        pf->fd_width  = open(path, O_RDONLY|O_BINARY);
+        pf->fd_offset = open(path, O_RDONLY|O_BINARY);
+        
         glyph_cache_load(font_id);
+        
+        if(pf->fd_width >= 0)
+            close(pf->fd_width);
+        pf->fd_width = -1;
+        
+        if(pf->fd_offset >= 0)
+            close(pf->fd_offset);
+        pf->fd_offset = -1;
     }
     else
     {
@@ -402,6 +417,8 @@ static bool internal_load_font(int font_id, const char *path, char *buf,
         pf->buffer_end = pf->buffer_position + size;
         close(pf->fd);
         pf->fd = -1;
+        pf->fd_width = -1;
+        pf->fd_offset = -1;
 
         if (!font_load_header(pf))
         {
@@ -451,6 +468,8 @@ static int alloc_and_init(int font_idx, const char* name, size_t size)
     pdata->refcount = 1;
     pf->buffer_position = pf->buffer_start = buffer_from_handle(handle);
     pf->buffer_size = size;
+    pf->fd_width = -1;
+    pf->fd_offset = -1;
     return handle;
 }
 
@@ -639,14 +658,20 @@ load_cache_entry(struct font_cache_entry* p, void* callback_data)
     int handle = pf_to_handle(pf);
     unsigned short char_code = p->_char_code;
     unsigned char tmp[2];
+    int fd;
 
     if (handle > 0)
         lock_font_handle(handle, true);
     if (pf->file_width_offset)
     {
         int width_offset = pf->file_width_offset + char_code;
-        lseek(pf->fd, width_offset, SEEK_SET);
-        read(pf->fd, &(p->width), 1);
+        /* load via different fd to get this file section cached */
+        if(pf->fd_width >=0 )
+            fd = pf->fd_width;
+        else
+            fd = pf->fd;
+        lseek(fd, width_offset, SEEK_SET);
+        read(fd, &(p->width), 1);
     }
     else
     {
@@ -658,11 +683,16 @@ load_cache_entry(struct font_cache_entry* p, void* callback_data)
     if (pf->file_offset_offset)
     {
         int32_t offset = pf->file_offset_offset + char_code * (pf->long_offset ? sizeof(int32_t) : sizeof(int16_t));
-        lseek(pf->fd, offset, SEEK_SET);
-        read (pf->fd, tmp, 2);
+        /* load via different fd to get this file section cached */
+        if(pf->fd_offset >=0 )
+            fd = pf->fd_offset;
+        else
+            fd = pf->fd;
+        lseek(fd, offset, SEEK_SET);
+        read (fd, tmp, 2);
         bitmap_offset = tmp[0] | (tmp[1] << 8);
         if (pf->long_offset) {
-            read (pf->fd, tmp, 2);
+            read (fd, tmp, 2);
             bitmap_offset |= (tmp[0] << 16) | (tmp[1] << 24);
         }
     }