minimal C implementation of modbus slave device
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modbus-slave/src/pp/payload_builder.c

87 lines
2.3 KiB

#include <string.h>
#include "pp/payload_builder.h"
#define pb_check_capacity(pb, needed) \
if ((pb)->current + (needed) > (pb)->end) { \
if ((pb)->full_handler == NULL || !(pb)->full_handler((pb), (needed))) { \
(pb)->ok = 0; \
} \
}
/** Write from a buffer */
bool pb_buf(PayloadBuilder *pb, const uint8_t *buf, uint32_t len)
{
pb_check_capacity(pb, len);
if (!pb->ok) { return false; }
memcpy(pb->current, buf, len);
pb->current += len;
return true;
}
/** Write s zero terminated string */
bool pb_string(PayloadBuilder *pb, const char *str)
{
uint32_t len = (uint32_t) strlen(str);
pb_check_capacity(pb, len + 1);
if (!pb->ok) {
return false;
}
memcpy(pb->current, str, len + 1);
pb->current += len + 1;
return true;
}
/** Write uint8_t to the buffer */
bool pb_u8(PayloadBuilder *pb, uint8_t byte)
{
pb_check_capacity(pb, 1);
if (!pb->ok) {
return false;
}
*pb->current++ = byte;
return true;
}
/** Write uint16_t to the buffer. */
bool pb_u16(PayloadBuilder *pb, uint16_t word)
{
pb_check_capacity(pb, 2);
if (!pb->ok) {
return false;
}
if (pb->bigendian) {
*pb->current++ = (uint8_t) ((word >> 8) & 0xFF);
*pb->current++ = (uint8_t) (word & 0xFF);
} else {
*pb->current++ = (uint8_t) (word & 0xFF);
*pb->current++ = (uint8_t) ((word >> 8) & 0xFF);
}
return true;
}
/** Write uint32_t to the buffer. */
bool pb_u32(PayloadBuilder *pb, uint32_t word)
{
pb_check_capacity(pb, 4);
if (!pb->ok) {
return false;
}
if (pb->bigendian) {
*pb->current++ = (uint8_t) ((word >> 24) & 0xFF);
*pb->current++ = (uint8_t) ((word >> 16) & 0xFF);
*pb->current++ = (uint8_t) ((word >> 8) & 0xFF);
*pb->current++ = (uint8_t) (word & 0xFF);
} else {
*pb->current++ = (uint8_t) (word & 0xFF);
*pb->current++ = (uint8_t) ((word >> 8) & 0xFF);
*pb->current++ = (uint8_t) ((word >> 16) & 0xFF);
*pb->current++ = (uint8_t) ((word >> 24) & 0xFF);
}
return true;
}