From 93e748ac840da04b72f7ad02d4937f9ef09e4cb3 Mon Sep 17 00:00:00 2001 From: Bertrik Sikken Date: Sun, 25 Sep 2011 12:19:33 +0000 Subject: IAP: use a state machine for handling iap packets, based on FS#12135 git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30598 a1c6a512-1295-4272-9138-f99709370657 --- apps/iap.c | 144 ++++++++++++++++++++++++++++++++++---------------- firmware/export/iap.h | 2 +- 2 files changed, 100 insertions(+), 46 deletions(-) diff --git a/apps/iap.c b/apps/iap.c index eaee21bc89..6fe0a03281 100644 --- a/apps/iap.c +++ b/apps/iap.c @@ -21,6 +21,7 @@ #include #include +#include "panic.h" #include "iap.h" #include "button.h" #include "config.h" @@ -56,13 +57,32 @@ static int iap_repeatbtn = 0; static bool iap_btnrepeat = false, iap_btnshuffle = false; static unsigned char serbuf[RX_BUFLEN]; -static int serbuf_i = 0; static unsigned char response[TX_BUFLEN]; -static int responselen; static char cur_dbrecord[5] = {0}; +/* states of the iap de-framing state machine */ +enum fsm_state { + ST_SYNC, /* wait for 0xFF sync byte */ + ST_SOF, /* wait for 0x55 start-of-frame byte */ + ST_LEN, /* receive length byte (small packet) */ + ST_LENH, /* receive length high byte (large packet) */ + ST_LENL, /* receive length low byte (large packet) */ + ST_DATA, /* receive data */ + ST_CHECK /* verify checksum */ +}; + +static struct state_t { + enum fsm_state state; /* current fsm state */ + unsigned int len; /* payload data length */ + unsigned char *payload; /* payload data pointer */ + unsigned int check; /* running checksum over [len,payload,check] */ + unsigned int count; /* playload bytes counter */ +} frame_state = { + .state = ST_SYNC +}; + static void put_u32(unsigned char *buf, uint32_t data) { buf[0] = (data >> 24) & 0xFF; @@ -142,7 +162,7 @@ void iap_bitrate_set(int ratenum) void iap_send_pkt(const unsigned char * data, int len) { - int i, chksum; + int i, chksum, responselen; if(len > TX_BUFLEN-4) len = TX_BUFLEN-4; responselen = len + 4; @@ -168,37 +188,75 @@ void iap_send_pkt(const unsigned char * data, int len) bool iap_getc(unsigned char x) { - static unsigned char last_x = 0; - static bool newpkt = true; - static unsigned char chksum = 0; - - /* Restart if the sync word is seen */ - if(x == 0x55 && last_x == 0xff/* && newpkt*/) - { - serbuf[0] = 0; - serbuf_i = 0; - chksum = 0; - newpkt = false; - } - else - { - if(serbuf_i >= RX_BUFLEN) - serbuf_i = 0; - - serbuf[serbuf_i++] = x; - chksum += x; - } - last_x = x; - - /* Broadcast to queue if we have a complete message */ - if(serbuf_i && (serbuf_i == serbuf[0]+2)) - { - serbuf_i = 0; - newpkt = true; - if(chksum == 0) + struct state_t *s = &frame_state; + + /* run state machine to detect and extract a valid frame */ + switch (s->state) { + case ST_SYNC: + if (x == 0xFF) { + s->state = ST_SOF; + } + break; + case ST_SOF: + if (x == 0x55) { + /* received a valid sync/SOF pair */ + s->state = ST_LEN; + } else { + s->state = ST_SYNC; + return iap_getc(x); + } + break; + case ST_LEN: + s->check = x; + s->count = 0; + s->payload = serbuf; + if (x == 0) { + /* large packet */ + s->state = ST_LENH; + } else { + /* small packet */ + s->len = x; + s->state = ST_DATA; + } + break; + case ST_LENH: + s->check += x; + s->len = x << 8; + s->state = ST_LENL; + break; + case ST_LENL: + s->check += x; + s->len += x; + if ((s->len == 0) || (s->len > RX_BUFLEN)) { + /* invalid length */ + s->state = ST_SYNC; + return iap_getc(x); + } else { + s->state = ST_DATA; + } + break; + case ST_DATA: + s->check += x; + s->payload[s->count++] = x; + if (s->count == s->len) { + s->state = ST_CHECK; + } + break; + case ST_CHECK: + s->check += x; + if ((s->check & 0xFF) == 0) { + /* done, received a valid frame */ queue_post(&button_queue, SYS_IAP_HANDLEPKT, 0); + } + s->state = ST_SYNC; + break; + default: + panicf("Unhandled iap state %d", (int) s->state); + break; } - return newpkt; + + /* return true while still hunting for the sync and start-of-frame byte */ + return (s->state == ST_SYNC) || (s->state == ST_SOF); } void iap_periodic(void) @@ -1004,8 +1062,9 @@ static void iap_handlepkt_mode7(unsigned int len, const unsigned char *buf) void iap_handlepkt(void) { + struct state_t *s = &frame_state; + if(!iap_setupflag) return; - if(serbuf[0] == 0) return; /* if we are waiting for a remote button to go out, delay the handling of the new packet */ @@ -1015,20 +1074,15 @@ void iap_handlepkt(void) return; } - /* get length and payload from serbuf */ - unsigned int len = serbuf[0]; - unsigned char *payload = &serbuf[1]; - - unsigned char mode = payload[0]; + /* handle command by mode */ + unsigned char mode = s->payload[0]; switch (mode) { - case 0: iap_handlepkt_mode0(len, payload); break; - case 2: iap_handlepkt_mode2(len, payload); break; - case 3: iap_handlepkt_mode3(len, payload); break; - case 4: iap_handlepkt_mode4(len, payload); break; - case 7: iap_handlepkt_mode7(len, payload); break; + case 0: iap_handlepkt_mode0(s->len, s->payload); break; + case 2: iap_handlepkt_mode2(s->len, s->payload); break; + case 3: iap_handlepkt_mode3(s->len, s->payload); break; + case 4: iap_handlepkt_mode4(s->len, s->payload); break; + case 7: iap_handlepkt_mode7(s->len, s->payload); break; } - - serbuf[0] = 0; } int remote_control_rx(void) diff --git a/firmware/export/iap.h b/firmware/export/iap.h index c9a670a05f..8ee26cbe9f 100644 --- a/firmware/export/iap.h +++ b/firmware/export/iap.h @@ -22,7 +22,7 @@ #include -#define RX_BUFLEN 260 +#define RX_BUFLEN 512 #define TX_BUFLEN 128 extern bool iap_getc(unsigned char x); 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