view libtwamr/if1_pack.c @ 477:4c9222d95647

libtwamr encoder: always emit frame->mode = mode; In the original implementation of amr_encode_frame(), the 'mode' member of the output struct was set to 0xFF if the output frame type is TX_NO_DATA. This design was made to mimic the mode field (16-bit word) being set to 0xFFFF (or -1) in 3GPP test sequence format - but nothing actually depends on this struct member being set in any way, and amr_frame_to_tseq() generates the needed 0xFFFF on its own, based on frame->type being equal to TX_NO_DATA. It is simpler and more efficient to always set frame->mode to the actual encoding mode in amr_encode_frame(), and this new behavior has already been documented in doc/AMR-library-API description in anticipation of the present change.
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 18 May 2024 22:30:42 +0000
parents ebe499058c63
children
line wrap: on
line source

/*
 * In this module we implement our function for packing AMR codec bits
 * from an array containing them in the codec's natural bit order
 * into the octet form of AMR IF1 and RFC 4867.
 */

#include <stdint.h>
#include "tw_amr.h"
#include "typedef.h"
#include "namespace.h"
#include "int_defs.h"
#include "if1_func.h"

static inline void msb_set_bit(uint8_t *buf, Word16 bn, Word16 bit)
{
	Word16 pos_byte = bn >> 3;
	Word16 pos_bit  = 7 - (bn & 7);

	if (bit)
		buf[pos_byte] |= (1 << pos_bit);
	else
		buf[pos_byte] &= ~(1 << pos_bit);
}

static void pack_bits(uint8_t *if1_bytes, const Word16 *src_bits, Word16 nbits,
		      const uint8_t *table)
{
	Word16 n, nb;

	for (n = 0; n < nbits; n++) {
		if (table)
			nb = table[n];
		else
			nb = n;
		msb_set_bit(if1_bytes, n, src_bits[nb]);
	}
}

void if1_pack_bytes(enum Mode mode, const Word16 *serial_bits,
		    uint8_t *if1_bytes)
{
	switch (mode) {
	case MR475:
		pack_bits(if1_bytes, serial_bits, AMR_NBITS_475, sort_475);
		if1_bytes[11] &= 0xFE;
		return;
	case MR515:
		pack_bits(if1_bytes, serial_bits, AMR_NBITS_515, sort_515);
		if1_bytes[12] &= 0xFE;
		return;
	case MR59:
		pack_bits(if1_bytes, serial_bits, AMR_NBITS_59, sort_59);
		if1_bytes[14] &= 0xFC;
		return;
	case MR67:
		pack_bits(if1_bytes, serial_bits, AMR_NBITS_67, sort_67);
		if1_bytes[16] &= 0xFC;
		return;
	case MR74:
		pack_bits(if1_bytes, serial_bits, AMR_NBITS_74, sort_74);
		if1_bytes[18] &= 0xF0;
		return;
	case MR795:
		pack_bits(if1_bytes, serial_bits, AMR_NBITS_795, sort_795);
		if1_bytes[19] &= 0xFE;
		return;
	case MR102:
		pack_bits(if1_bytes, serial_bits, AMR_NBITS_102, sort_102);
		if1_bytes[25] &= 0xF0;
		return;
	case MR122:            
		pack_bits(if1_bytes, serial_bits, AMR_NBITS_122, sort_122);
		if1_bytes[30] &= 0xF0;
		return;
	case MRDTX:
		pack_bits(if1_bytes, serial_bits, AMR_NBITS_SID,
				(const uint8_t *) 0);
		if1_bytes[4] &= 0xE0;
		return;
	}
}