#include <stdio.h>
#include <stdint.h>

struct stRequestMsg {
    uint16_t startTag;
    uint32_t messageSize;
    uint16_t messageID;
    uint16_t sequenceNumber;
    uint16_t messageType;
    uint32_t reserved;
};

void printIt(struct stRequestMsg m) {
	printf("{\n"
	       "  .startTag =       %#x;\n"
	       "  .messageSize =    %#x;\n"
	       "  .messageID =      %#x;\n"
	       "  .sequenceNumber = %#x;\n"
	       "  .messageType =    %#x;\n"
	       "  .reserved =       %#x;\n"
	       "}\n",
	       m.startTag, m.messageSize, m.messageID,
	       m.sequenceNumber, m.messageType, m.reserved);
}


uint16_t deserialize_uint16(char const * const b) {
	return ((uint16_t) b[0] << 8u) |
	       ((uint16_t) b[1]);
}
uint32_t deserialize_uint32(char const * const b) {
	return ((uint16_t) b[0] << 24u) |
	       ((uint16_t) b[1] << 16u) |
	       ((uint16_t) b[2] << 8u) |
	       ((uint16_t) b[3]);
}

struct stRequestMsg deserialize(char const * const b) {
	struct stRequestMsg r;
	r.startTag = deserialize_uint16(b);
	r.messageSize = deserialize_uint32(b + 2);
	r.messageID = deserialize_uint16(b + 6);
	r.sequenceNumber = deserialize_uint16(b + 8);
	r.messageType = deserialize_uint16(b + 10);
	r.reserved = deserialize_uint32(b + 12);
	return r;
}

int main(void) {
  char buff[16];
  buff[0] = 0x50;
  buff[1] = 0x00;
  buff[2] = 0x1E;
  buff[3] = 0x00;
  buff[4] = 0x00;
  buff[5] = 0x00;
  buff[6] = 0x31;
  buff[7] = 0x00;
  buff[8] = 0x10;
  buff[9] = 0x00;
  buff[10] = 0x20;
  buff[11] = 0x00;
  buff[12] = 0x10;
  buff[13] = 0x00;
  buff[14] = 0x00;
  buff[15] = 0x00;
  
  struct stRequestMsg msg = deserialize(&(buff[0]));
  printIt(msg);
  return 0;
}