/*
 * Here we implement parsing/decoding of TRAU-AMR-8k frames per 3GPP TS 48.061,
 * striving to decode and display as much as we can.
 */

#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include "osmo_bits.h"

/*
 * AMR TRAU parity (same as EFR)
 *
 * g(x) = x^3 + x^1 + 1
 */
static const struct osmo_crc8gen_code gsm0860_amr_crc3 = {
	.bits = 3,
	.poly = 0x3,
	.init = 0x0,
	.remainder = 0x7,
};

static int saved_mode, saved_mode_valid;

static char *fclass_names[4] = {
	"No_Speech", "Speech_Bad", "Speech_Degraded", "Speech_Good"
};

static char *nospch_class_names[8] = {
	"No_Data", "invalid", "invalid", "invalid",
	"Sid_Bad", "Sid_Update", "Onset", "Sid_First"
};

static const uint8_t params_lsf_475_515[] = {8, 8, 7, 0};
static const uint8_t params_lsf_59_67_74[] = {8, 9, 9, 0};

static const uint8_t params_475_sf1[]  = {8, 7, 2, 8, 0};
static const uint8_t params_475_sf3[]  = {4, 7, 2, 8, 0};
static const uint8_t params_475_sf24[] = {4, 7, 2, 0};

static const uint8_t params_515_sf1[]   = {8, 7, 2, 6, 0};
static const uint8_t params_515_sf234[] = {4, 7, 2, 6, 0};

static const uint8_t params_59_sf13[] = {8, 9, 2, 6, 0};
static const uint8_t params_59_sf24[] = {4, 9, 2, 6, 0};

static const uint8_t params_67_sf13[] = {8, 11, 3, 7, 0};
static const uint8_t params_67_sf24[] = {4, 11, 3, 7, 0};

static const uint8_t params_74_sf13[] = {8, 13, 4, 7, 0};
static const uint8_t params_74_sf24[] = {5, 13, 4, 7, 0};

static const uint8_t params_sid[] = {3, 8, 9, 9, 6, 0};

static const ubit_t bit8_0[8] = { 0, };

/*!< check sync pattern for AMR No_Speech + low bit rate */
static bool is_amr_low(const ubit_t *bits)
{
	int i;

	/* TS 08.61 Section 6.8.2.1.2 */
	if (memcmp(bits, bit8_0, sizeof(bit8_0)))
		return false;
	if (bits[8] != 1)
		return false;
	if (bits[16] != 1)
		return false;
	if (bits[24] != 0 || bits[25] != 1)
		return false;
	for (i = 32; i < 20 * 8; i += 8) {
		if (bits[i] != 1)
			return false;
	}
	return true;
}

/*!< check sync pattern for AMR 6.7kBit/s */
static bool is_amr_67(const ubit_t *bits)
{
	int i;

	/* TS 08.61 Section 6.8.2.1.3 */
	if (memcmp(bits, bit8_0, sizeof(bit8_0)))
		return false;
	if (bits[8] != 1)
		return false;
	if (bits[16] != 1)
		return false;
	if (bits[24] != 1)
		return false;
	if (bits[32] != 1)
		return false;
	if (bits[40] != 0)
		return false;
	for (i = 48; i < 20 * 8; i += 16) {
		if (bits[i] != 1)
			return false;
	}
	return true;
}

/*!< check sync pattern for AMR 7.4kBit/s */
static bool is_amr_74(const ubit_t *bits)
{
	if (bits[0] != 0 || bits[1] != 0 || bits[2] != 1)
		return false;
	if (bits[8] != 0)
		return false;
	if (bits[16] != 1)
		return false;
	if (bits[24] != 0)
		return false;

	return true;
}

static unsigned
bits_to_num(bits, nbits)
	ubit_t *bits;
	unsigned nbits;
{
	unsigned accum;
	unsigned n;

	accum = 0;
	for (n = 0; n < nbits; n++) {
		accum <<= 1;
		if (*bits)
			accum |= 1;
		bits++;
	}
	return accum;
}

static void
print_generic_params(bits, ltab)
	ubit_t *bits;
	uint8_t *ltab;
{
	uint8_t *tp;
	unsigned n, p;

	for (tp = ltab; n = *tp; tp++) {
		p = bits_to_num(bits, n);
		bits += n;
		printf(" %u", p);
	}
}

static void
print_speech_params(bits, ltab)
	ubit_t *bits;
	uint8_t *ltab;
{
	fputs("   ", stdout);
	print_generic_params(bits, ltab);
	putchar('\n');
}

static void
check_spare_bits(bits, nbits, desc)
	ubit_t *bits;
	unsigned nbits;
	char *desc;
{
	while (nbits) {
		if (*bits == 0)
			break;
		bits++;
		nbits--;
	}
	if (!nbits)
		return;
	printf("    Extra data in bits %s\n", desc);
}

static void
handle_amr8_low(frame_bits)
	ubit_t *frame_bits;
{
	puts("  TRAU-AMR-8k Low format, decoding to be implemented");
}

static void
handle_amr8_6k7(frame_bits)
	ubit_t *frame_bits;
{
	puts("  TRAU-AMR-8k MR67 format, decoding to be implemented");
}

static void
handle_amr8_7k4(frame_bits)
	ubit_t *frame_bits;
{
	puts("  TRAU-AMR-8k MR74 format, decoding to be implemented");
}

void
print_amr8_frame(frame_bits)
	ubit_t *frame_bits;
{
	if (is_amr_low(frame_bits))
		handle_amr8_low(frame_bits);
	else if (is_amr_67(frame_bits))
		handle_amr8_6k7(frame_bits);
	else if (is_amr_74(frame_bits))
		handle_amr8_7k4(frame_bits);
	else
		puts("  Unrecognized format by sync pattern");
}