A simple library for building and parsing data frames for serial interfaces (like UART / RS232)
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TinyFrame/utilities/payload_parser.c

121 lines
2.6 KiB

#include "payload_parser.h"
#define pp_check_capacity(pp, needed) \
if ((pp)->current + (needed) > (pp)->end) { \
if ((pp)->empty_handler == NULL || !(pp)->empty_handler(pp, needed)) {(pp)->ok = 0;} ; \
}
void pp_skip(PayloadParser *pp, uint32_t num)
{
pp->current += num;
}
uint8_t pp_u8(PayloadParser *pp)
{
pp_check_capacity(pp, 1);
if (!pp->ok) return 0;
return *pp->current++;
}
uint16_t pp_u16(PayloadParser *pp)
{
pp_check_capacity(pp, 2);
if (!pp->ok) return 0;
uint16_t x = 0;
if (pp->bigendian) {
x |= *pp->current++ << 8;
x |= *pp->current++;
} else {
x |= *pp->current++;
x |= *pp->current++ << 8;
}
return x;
}
uint32_t pp_u32(PayloadParser *pp)
{
pp_check_capacity(pp, 4);
if (!pp->ok) return 0;
uint32_t x = 0;
if (pp->bigendian) {
x |= (uint32_t) (*pp->current++ << 24);
x |= (uint32_t) (*pp->current++ << 16);
x |= (uint32_t) (*pp->current++ << 8);
x |= *pp->current++;
} else {
x |= *pp->current++;
x |= (uint32_t) (*pp->current++ << 8);
x |= (uint32_t) (*pp->current++ << 16);
x |= (uint32_t) (*pp->current++ << 24);
}
return x;
}
const uint8_t *pp_tail(PayloadParser *pp, uint32_t *length)
{
int32_t len = (int) (pp->end - pp->current);
if (!pp->ok || len <= 0) {
if (length != NULL) *length = 0;
return NULL;
}
if (length != NULL) {
*length = (uint32_t) len;
}
return pp->current;
}
/** Read int8_t from the payload. */
int8_t pp_i8(PayloadParser *pp)
{
return ((union conv8) {.u8 = pp_u8(pp)}).i8;
}
/** Read int16_t from the payload. */
int16_t pp_i16(PayloadParser *pp)
{
return ((union conv16) {.u16 = pp_u16(pp)}).i16;
}
/** Read int32_t from the payload. */
int32_t pp_i32(PayloadParser *pp)
{
return ((union conv32) {.u32 = pp_u32(pp)}).i32;
}
/** Read 4-byte float from the payload. */
float pp_float(PayloadParser *pp)
{
return ((union conv32) {.u32 = pp_u32(pp)}).f32;
}
/** Read a zstring */
uint32_t pp_string(PayloadParser *pp, char *buffer, uint32_t maxlen)
{
pp_check_capacity(pp, 1);
uint32_t len = 0;
while (len < maxlen-1 && pp->current != pp->end) {
char c = *buffer++ = *pp->current++;
if (c == 0) break;
len++;
}
*buffer = 0;
return len;
}
/** Read a buffer */
uint32_t pp_buf(PayloadParser *pp, uint8_t *buffer, uint32_t maxlen)
{
uint32_t len = 0;
while (len < maxlen && pp->current != pp->end) {
*buffer++ = *pp->current++;
len++;
}
return len;
}