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klipper-dgus/src/command.c

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// Code for parsing incoming commands and encoding outgoing messages
//
// Copyright (C) 2016,2017 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include <stdarg.h> // va_start
#include <string.h> // memcpy
#include "board/io.h" // readb
#include "board/irq.h" // irq_poll
#include "board/misc.h" // crc16_ccitt
#include "board/pgm.h" // READP
#include "command.h" // output_P
#include "sched.h" // sched_is_shutdown
static uint8_t next_sequence = MESSAGE_DEST;
static uint32_t
command_encode_ptr(void *p)
{
if (sizeof(size_t) > sizeof(uint32_t))
return p - console_receive_buffer();
return (size_t)p;
}
void *
command_decode_ptr(uint32_t v)
{
if (sizeof(size_t) > sizeof(uint32_t))
return console_receive_buffer() + v;
return (void*)(size_t)v;
}
/****************************************************************
* Binary message parsing
****************************************************************/
// Encode an integer as a variable length quantity (vlq)
static uint8_t *
encode_int(uint8_t *p, uint32_t v)
{
int32_t sv = v;
if (sv < (3L<<5) && sv >= -(1L<<5)) goto f4;
if (sv < (3L<<12) && sv >= -(1L<<12)) goto f3;
if (sv < (3L<<19) && sv >= -(1L<<19)) goto f2;
if (sv < (3L<<26) && sv >= -(1L<<26)) goto f1;
*p++ = (v>>28) | 0x80;
f1: *p++ = ((v>>21) & 0x7f) | 0x80;
f2: *p++ = ((v>>14) & 0x7f) | 0x80;
f3: *p++ = ((v>>7) & 0x7f) | 0x80;
f4: *p++ = v & 0x7f;
return p;
}
// Parse an integer that was encoded as a "variable length quantity"
static uint32_t
parse_int(uint8_t **pp)
{
uint8_t *p = *pp, c = *p++;
uint32_t v = c & 0x7f;
if ((c & 0x60) == 0x60)
v |= -0x20;
while (c & 0x80) {
c = *p++;
v = (v<<7) | (c & 0x7f);
}
*pp = p;
return v;
}
// Parse an incoming command into 'args'
uint8_t *
command_parsef(uint8_t *p, uint8_t *maxend
, const struct command_parser *cp, uint32_t *args)
{
uint_fast8_t num_params = READP(cp->num_params);
const uint8_t *param_types = READP(cp->param_types);
while (num_params--) {
if (p > maxend)
goto error;
uint_fast8_t t = READP(*param_types);
param_types++;
switch (t) {
case PT_uint32:
case PT_int32:
case PT_uint16:
case PT_int16:
case PT_byte:
*args++ = parse_int(&p);
break;
case PT_buffer: {
uint_fast8_t len = *p++;
if (p + len > maxend)
goto error;
*args++ = len;
*args++ = command_encode_ptr(p);
p += len;
break;
}
default:
goto error;
}
}
return p;
error:
shutdown("Command parser error");
}
// Encode a message
static uint_fast8_t
command_encodef(uint8_t *buf, const struct command_encoder *ce, va_list args)
{
uint_fast8_t max_size = READP(ce->max_size);
if (max_size <= MESSAGE_MIN)
// Ack/Nak message
return max_size;
uint8_t *p = &buf[MESSAGE_HEADER_SIZE];
uint8_t *maxend = &p[max_size - MESSAGE_MIN];
uint_fast8_t num_params = READP(ce->num_params);
const uint8_t *param_types = READP(ce->param_types);
*p++ = READP(ce->msg_id);
while (num_params--) {
if (p > maxend)
goto error;
uint_fast8_t t = READP(*param_types);
param_types++;
uint32_t v;
switch (t) {
case PT_uint32:
case PT_int32:
case PT_uint16:
case PT_int16:
case PT_byte:
if (sizeof(v) > sizeof(int) && t >= PT_uint16)
if (t == PT_int16)
v = (int32_t)va_arg(args, int);
else
v = va_arg(args, unsigned int);
else
v = va_arg(args, uint32_t);
p = encode_int(p, v);
break;
case PT_string: {
uint8_t *s = va_arg(args, uint8_t*), *lenp = p++;
while (*s && p<maxend)
*p++ = *s++;
*lenp = p-lenp-1;
break;
}
case PT_progmem_buffer:
case PT_buffer: {
v = va_arg(args, int);
if (v > maxend-p)
v = maxend-p;
*p++ = v;
uint8_t *s = va_arg(args, uint8_t*);
if (t == PT_progmem_buffer)
memcpy_P(p, s, v);
else
memcpy(p, s, v);
p += v;
break;
}
default:
goto error;
}
}
return p - buf + MESSAGE_TRAILER_SIZE;
error:
shutdown("Message encode error");
}
// Add header and trailer bytes to a message block
static void
command_add_frame(uint8_t *buf, uint_fast8_t msglen)
{
buf[MESSAGE_POS_LEN] = msglen;
buf[MESSAGE_POS_SEQ] = next_sequence;
uint16_t crc = crc16_ccitt(buf, msglen - MESSAGE_TRAILER_SIZE);
buf[msglen - MESSAGE_TRAILER_CRC + 0] = crc >> 8;
buf[msglen - MESSAGE_TRAILER_CRC + 1] = crc;
buf[msglen - MESSAGE_TRAILER_SYNC] = MESSAGE_SYNC;
}
// Encode a message and then add a message block frame around it
uint_fast8_t
command_encode_and_frame(uint8_t *buf, const struct command_encoder *ce
, va_list args)
{
uint_fast8_t msglen = command_encodef(buf, ce, args);
command_add_frame(buf, msglen);
return msglen;
}
static uint8_t in_sendf;
// Encode and transmit a "response" message
void
command_sendf(const struct command_encoder *ce, ...)
{
if (readb(&in_sendf))
// This sendf call was made from an irq handler while the main
// code was already in sendf - just drop this sendf request.
return;
writeb(&in_sendf, 1);
va_list args;
va_start(args, ce);
console_sendf(ce, args);
va_end(args);
writeb(&in_sendf, 0);
}
void
sendf_shutdown(void)
{
writeb(&in_sendf, 0);
}
DECL_SHUTDOWN(sendf_shutdown);
/****************************************************************
* Command routing
****************************************************************/
// Find the command handler associated with a command
static const struct command_parser *
command_lookup_parser(uint_fast8_t cmdid)
{
if (!cmdid || cmdid >= READP(command_index_size))
shutdown("Invalid command");
return &command_index[cmdid];
}
// Empty message (for ack/nak transmission)
const struct command_encoder encode_acknak PROGMEM = {
.max_size = MESSAGE_MIN,
};
enum { CF_NEED_SYNC=1<<0, CF_NEED_VALID=1<<1 };
// Find the next complete message block
int_fast8_t
command_find_block(uint8_t *buf, uint_fast8_t buf_len, uint_fast8_t *pop_count)
{
static uint8_t sync_state;
if (buf_len && sync_state & CF_NEED_SYNC)
goto need_sync;
if (buf_len < MESSAGE_MIN)
goto need_more_data;
uint_fast8_t msglen = buf[MESSAGE_POS_LEN];
if (msglen < MESSAGE_MIN || msglen > MESSAGE_MAX)
goto error;
uint_fast8_t msgseq = buf[MESSAGE_POS_SEQ];
if ((msgseq & ~MESSAGE_SEQ_MASK) != MESSAGE_DEST)
goto error;
if (buf_len < msglen)
goto need_more_data;
if (buf[msglen-MESSAGE_TRAILER_SYNC] != MESSAGE_SYNC)
goto error;
uint16_t msgcrc = ((buf[msglen-MESSAGE_TRAILER_CRC] << 8)
| buf[msglen-MESSAGE_TRAILER_CRC+1]);
uint16_t crc = crc16_ccitt(buf, msglen-MESSAGE_TRAILER_SIZE);
if (crc != msgcrc)
goto error;
sync_state &= ~CF_NEED_VALID;
*pop_count = msglen;
// Check sequence number
if (msgseq != next_sequence) {
// Lost message - discard messages until it is retransmitted
goto nak;
}
next_sequence = ((msgseq + 1) & MESSAGE_SEQ_MASK) | MESSAGE_DEST;
return 1;
need_more_data:
*pop_count = 0;
return 0;
error:
if (buf[0] == MESSAGE_SYNC) {
// Ignore (do not nak) leading SYNC bytes
*pop_count = 1;
return -1;
}
sync_state |= CF_NEED_SYNC;
need_sync: ;
// Discard bytes until next SYNC found
uint8_t *next_sync = memchr(buf, MESSAGE_SYNC, buf_len);
if (next_sync) {
sync_state &= ~CF_NEED_SYNC;
*pop_count = next_sync - buf + 1;
} else {
*pop_count = buf_len;
}
if (sync_state & CF_NEED_VALID)
return -1;
sync_state |= CF_NEED_VALID;
nak:
command_sendf(&encode_acknak);
return -1;
}
// Dispatch all the commands found in a message block
void
command_dispatch(uint8_t *buf, uint_fast8_t msglen)
{
uint8_t *p = &buf[MESSAGE_HEADER_SIZE];
uint8_t *msgend = &buf[msglen-MESSAGE_TRAILER_SIZE];
while (p < msgend) {
uint_fast8_t cmdid = *p++;
const struct command_parser *cp = command_lookup_parser(cmdid);
uint32_t args[READP(cp->num_args)];
p = command_parsef(p, msgend, cp, args);
if (sched_is_shutdown() && !(READP(cp->flags) & HF_IN_SHUTDOWN)) {
sched_report_shutdown();
continue;
}
irq_poll();
void (*func)(uint32_t*) = READP(cp->func);
func(args);
}
}
// Send an ack message to the host (notifying that it can send more data)
void
command_send_ack(void)
{
command_sendf(&encode_acknak);
}
// Find a message block and then dispatch all the commands in it
int_fast8_t
command_find_and_dispatch(uint8_t *buf, uint_fast8_t buf_len
, uint_fast8_t *pop_count)
{
int_fast8_t ret = command_find_block(buf, buf_len, pop_count);
if (ret > 0) {
command_dispatch(buf, *pop_count);
command_send_ack();
}
return ret;
}
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