Byte array utils

Reading

Retrieve uint16_t or uint32_t values from a byte array interpreted as uint8_t in big-endian order.

	inline uint8_t G_BYTE(const uint8_t*& p) {
		return *(p)++;
	}
	inline uint16_t G_WORD(const uint8_t*& p) {
		uint32_t r = *p++;
		r = (r << 8) + *p++;
		return r;
	}
	inline uint32_t G_DWORD(const uint8_t*& p) {
		uint32_t r = *p++;
		r = (r << 8) + *p++;
		r = (r << 8) + *p++;
		r = (r << 8) + *p++;
		return r;
	}

p is incremented by the number of bytes read.

Writing

Writes uint8_t, uint16_t, or uint32_t values in big-endian order to the byte array pointed to by q.

	inline uint8_t& S_OCTET(uint8_t*& q, uint8_t c) {
		*q++ = c;
		return *q;
	}
	inline uint8_t& S_WORD(uint8_t*& q, uint16_t c) {
		*(q) = ((c) >> 8) & 0xff; (q)++;
		*(q) = ((c) & 0xff); (q)++;
		return *q;
	}
	inline uint8_t& S_DWORD(uint8_t*& q, uint32_t c) {
		*(q) = ((c) >> 24) & 0xff; (q)++;
		*(q) = ((c) >> 16) & 0xff; (q)++;
		*(q) = ((c) >>  8) & 0xff; (q)++;
		*(q) = ((c) & 0xff); (q)++;
		return *q;
	}

q is incremented by the number of bytes written.

Background

These utilities simplify operations during the construction and decomposition of data payloads in wireless packets.

You may also use the simplified pack_bytes() and expand_bytes() functions.