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view frtest/tidsp.c @ 242:f081a6850fb5

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libgsmfrp: new refined implementation The previous implementation exhibited the following defects, which are now fixed: 1) The last received valid SID was cached forever for the purpose of handling future invalid SIDs - we could have received some valid SID ages ago, then lots of speech or NO_DATA, and if we then get an invalid SID, we would resurrect the last valid SID from ancient history - a bad design. In our new design, we handle invalid SID based on the current state, much like BFI. 2) GSM 06.11 spec says clearly that after the second lost SID (received BFI=1 && TAF=1 in CN state) we need to gradually decrease the output level, rather than jump directly to emitting silence frames - we previously failed to implement such logic. 3) Per GSM 06.12 section 5.2, Xmaxc should be the same in all 4 subframes in a SID frame. What should we do if we receive an otherwise valid SID frame with different Xmaxc? Our previous approach would replicate this Xmaxc oddity in every subsequent generated CN frame, which is rather bad. In our new design, the very first CN frame (which can be seen as a transformation of the SID frame itself) retains the original 4 distinct Xmaxc, but all subsequent CN frames are based on the Xmaxc from the last subframe of the most recent SID.
author Mychaela Falconia <falcon@freecalypso.org>
date Tue, 09 May 2023 05:16:31 +0000
parents 7960744ba19c
children
line wrap: on
line source

/*
 * This code (lifted from OsmocomBB) facilitates the conversion of 33-byte
 * GSM 06.10 encoded speech frames between the bit order at the 06.10 interface
 * in the de facto standard libgsm implementation and the bit order at the
 * 05.03 channel encoder interface, as realized in TI's Calypso DSP.
 */

#include <sys/types.h>
#include <string.h>
#include <strings.h>

/* GSM FR - subjective importance bit ordering */
	/* This array encodes GSM 05.03 Table 2.
	 * It's also GSM 06.10 Table A.2.1a
	 *
	 * It converts between serial parameter output by the encoder and the
	 * order needed before channel encoding.
	 */
const u_short gsm0610_bitorder[260] = {
	0,	/* LARc0:5 */
	47,	/* Xmaxc0:5 */
	103,	/* Xmaxc1:5 */
	159,	/* Xmaxc2:5 */
	215,	/* Xmaxc3:5 */
	1,	/* LARc0:4 */
	6,	/* LARc1:5 */
	12,	/* LARc2:4 */
	2,	/* LARc0:3 */
	7,	/* LARc1:4 */
	13,	/* LARc2:3 */
	17,	/* LARc3:4 */
	36,	/* Nc0:6 */
	92,	/* Nc1:6 */
	148,	/* Nc2:6 */
	204,	/* Nc3:6 */
	48,	/* Xmaxc0:4 */
	104,	/* Xmaxc1:4 */
	160,	/* Xmaxc2:4 */
	216,	/* Xmaxc3:4 */
	8,	/* LARc1:3 */
	22,	/* LARc4:3 */
	26,	/* LARc5:3 */
	37,	/* Nc0:5 */
	93,	/* Nc1:5 */
	149,	/* Nc2:5 */
	205,	/* Nc3:5 */
	38,	/* Nc0:4 */
	94,	/* Nc1:4 */
	150,	/* Nc2:4 */
	206,	/* Nc3:4 */
	39,	/* Nc0:3 */
	95,	/* Nc1:3 */
	151,	/* Nc2:3 */
	207,	/* Nc3:3 */
	40,	/* Nc0:2 */
	96,	/* Nc1:2 */
	152,	/* Nc2:2 */
	208,	/* Nc3:2 */
	49,	/* Xmaxc0:3 */
	105,	/* Xmaxc1:3 */
	161,	/* Xmaxc2:3 */
	217,	/* Xmaxc3:3 */
	3,	/* LARc0:2 */
	18,	/* LARc3:3 */
	30,	/* LARc6:2 */
	41,	/* Nc0:1 */
	97,	/* Nc1:1 */
	153,	/* Nc2:1 */
	209,	/* Nc3:1 */
	23,	/* LARc4:2 */
	27,	/* LARc5:2 */
	43,	/* bc0:1 */
	99,	/* bc1:1 */
	155,	/* bc2:1 */
	211,	/* bc3:1 */
	42,	/* Nc0:0 */
	98,	/* Nc1:0 */
	154,	/* Nc2:0 */
	210,	/* Nc3:0 */
	45,	/* Mc0:1 */
	101,	/* Mc1:1 */
	157,	/* Mc2:1 */
	213,	/* Mc3:1 */
	4,	/* LARc0:1 */
	9,	/* LARc1:2 */
	14,	/* LARc2:2 */
	33,	/* LARc7:2 */
	19,	/* LARc3:2 */
	24,	/* LARc4:1 */
	31,	/* LARc6:1 */
	44,	/* bc0:0 */
	100,	/* bc1:0 */
	156,	/* bc2:0 */
	212,	/* bc3:0 */
	50,	/* Xmaxc0:2 */
	106,	/* Xmaxc1:2 */
	162,	/* Xmaxc2:2 */
	218,	/* Xmaxc3:2 */
	53,	/* xmc0_0:2 */
	56,	/* xmc0_1:2 */
	59,	/* xmc0_2:2 */
	62,	/* xmc0_3:2 */
	65,	/* xmc0_4:2 */
	68,	/* xmc0_5:2 */
	71,	/* xmc0_6:2 */
	74,	/* xmc0_7:2 */
	77,	/* xmc0_8:2 */
	80,	/* xmc0_9:2 */
	83,	/* xmc0_10:2 */
	86,	/* xmc0_11:2 */
	89,	/* xmc0_12:2 */
	109,	/* xmc1_0:2 */
	112,	/* xmc1_1:2 */
	115,	/* xmc1_2:2 */
	118,	/* xmc1_3:2 */
	121,	/* xmc1_4:2 */
	124,	/* xmc1_5:2 */
	127,	/* xmc1_6:2 */
	130,	/* xmc1_7:2 */
	133,	/* xmc1_8:2 */
	136,	/* xmc1_9:2 */
	139,	/* xmc1_10:2 */
	142,	/* xmc1_11:2 */
	145,	/* xmc1_12:2 */
	165,	/* xmc2_0:2 */
	168,	/* xmc2_1:2 */
	171,	/* xmc2_2:2 */
	174,	/* xmc2_3:2 */
	177,	/* xmc2_4:2 */
	180,	/* xmc2_5:2 */
	183,	/* xmc2_6:2 */
	186,	/* xmc2_7:2 */
	189,	/* xmc2_8:2 */
	192,	/* xmc2_9:2 */
	195,	/* xmc2_10:2 */
	198,	/* xmc2_11:2 */
	201,	/* xmc2_12:2 */
	221,	/* xmc3_0:2 */
	224,	/* xmc3_1:2 */
	227,	/* xmc3_2:2 */
	230,	/* xmc3_3:2 */
	233,	/* xmc3_4:2 */
	236,	/* xmc3_5:2 */
	239,	/* xmc3_6:2 */
	242,	/* xmc3_7:2 */
	245,	/* xmc3_8:2 */
	248,	/* xmc3_9:2 */
	251,	/* xmc3_10:2 */
	254,	/* xmc3_11:2 */
	257,	/* xmc3_12:2 */
	46,	/* Mc0:0 */
	102,	/* Mc1:0 */
	158,	/* Mc2:0 */
	214,	/* Mc3:0 */
	51,	/* Xmaxc0:1 */
	107,	/* Xmaxc1:1 */
	163,	/* Xmaxc2:1 */
	219,	/* Xmaxc3:1 */
	54,	/* xmc0_0:1 */
	57,	/* xmc0_1:1 */
	60,	/* xmc0_2:1 */
	63,	/* xmc0_3:1 */
	66,	/* xmc0_4:1 */
	69,	/* xmc0_5:1 */
	72,	/* xmc0_6:1 */
	75,	/* xmc0_7:1 */
	78,	/* xmc0_8:1 */
	81,	/* xmc0_9:1 */
	84,	/* xmc0_10:1 */
	87,	/* xmc0_11:1 */
	90,	/* xmc0_12:1 */
	110,	/* xmc1_0:1 */
	113,	/* xmc1_1:1 */
	116,	/* xmc1_2:1 */
	119,	/* xmc1_3:1 */
	122,	/* xmc1_4:1 */
	125,	/* xmc1_5:1 */
	128,	/* xmc1_6:1 */
	131,	/* xmc1_7:1 */
	134,	/* xmc1_8:1 */
	137,	/* xmc1_9:1 */
	140,	/* xmc1_10:1 */
	143,	/* xmc1_11:1 */
	146,	/* xmc1_12:1 */
	166,	/* xmc2_0:1 */
	169,	/* xmc2_1:1 */
	172,	/* xmc2_2:1 */
	175,	/* xmc2_3:1 */
	178,	/* xmc2_4:1 */
	181,	/* xmc2_5:1 */
	184,	/* xmc2_6:1 */
	187,	/* xmc2_7:1 */
	190,	/* xmc2_8:1 */
	193,	/* xmc2_9:1 */
	196,	/* xmc2_10:1 */
	199,	/* xmc2_11:1 */
	202,	/* xmc2_12:1 */
	222,	/* xmc3_0:1 */
	225,	/* xmc3_1:1 */
	228,	/* xmc3_2:1 */
	231,	/* xmc3_3:1 */
	234,	/* xmc3_4:1 */
	237,	/* xmc3_5:1 */
	240,	/* xmc3_6:1 */
	243,	/* xmc3_7:1 */
	246,	/* xmc3_8:1 */
	249,	/* xmc3_9:1 */
	252,	/* xmc3_10:1 */
	255,	/* xmc3_11:1 */
	258,	/* xmc3_12:1 */
	5,	/* LARc0:0 */
	10,	/* LARc1:1 */
	15,	/* LARc2:1 */
	28,	/* LARc5:1 */
	32,	/* LARc6:0 */
	34,	/* LARc7:1 */
	35,	/* LARc7:0 */
	16,	/* LARc2:0 */
	20,	/* LARc3:1 */
	21,	/* LARc3:0 */
	25,	/* LARc4:0 */
	52,	/* Xmaxc0:0 */
	108,	/* Xmaxc1:0 */
	164,	/* Xmaxc2:0 */
	220,	/* Xmaxc3:0 */
	55,	/* xmc0_0:0 */
	58,	/* xmc0_1:0 */
	61,	/* xmc0_2:0 */
	64,	/* xmc0_3:0 */
	67,	/* xmc0_4:0 */
	70,	/* xmc0_5:0 */
	73,	/* xmc0_6:0 */
	76,	/* xmc0_7:0 */
	79,	/* xmc0_8:0 */
	82,	/* xmc0_9:0 */
	85,	/* xmc0_10:0 */
	88,	/* xmc0_11:0 */
	91,	/* xmc0_12:0 */
	111,	/* xmc1_0:0 */
	114,	/* xmc1_1:0 */
	117,	/* xmc1_2:0 */
	120,	/* xmc1_3:0 */
	123,	/* xmc1_4:0 */
	126,	/* xmc1_5:0 */
	129,	/* xmc1_6:0 */
	132,	/* xmc1_7:0 */
	135,	/* xmc1_8:0 */
	138,	/* xmc1_9:0 */
	141,	/* xmc1_10:0 */
	144,	/* xmc1_11:0 */
	147,	/* xmc1_12:0 */
	167,	/* xmc2_0:0 */
	170,	/* xmc2_1:0 */
	173,	/* xmc2_2:0 */
	176,	/* xmc2_3:0 */
	179,	/* xmc2_4:0 */
	182,	/* xmc2_5:0 */
	185,	/* xmc2_6:0 */
	188,	/* xmc2_7:0 */
	191,	/* xmc2_8:0 */
	194,	/* xmc2_9:0 */
	197,	/* xmc2_10:0 */
	200,	/* xmc2_11:0 */
	203,	/* xmc2_12:0 */
	223,	/* xmc3_0:0 */
	226,	/* xmc3_1:0 */
	229,	/* xmc3_2:0 */
	232,	/* xmc3_3:0 */
	235,	/* xmc3_4:0 */
	238,	/* xmc3_5:0 */
	241,	/* xmc3_6:0 */
	244,	/* xmc3_7:0 */
	247,	/* xmc3_8:0 */
	250,	/* xmc3_9:0 */
	253,	/* xmc3_10:0 */
	256,	/* xmc3_11:0 */
	259,	/* xmc3_12:0 */
	11,	/* LARc1:0 */
	29,	/* LARc5:0 */
};

static int
msb_get_bit(buf, bn)
	u_char *buf;
{
	int pos_byte = bn >> 3;
	int pos_bit  = 7 - (bn & 7);

	return (buf[pos_byte] >> pos_bit) & 1;
}

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

	buf[pos_byte] |= (bit << pos_bit);
}

void
gsm0610_tidsp_to_libgsm(inbytes, outbytes)
	u_char *inbytes, *outbytes;
{
	int i, di, si;

	bzero(outbytes, 33);
	outbytes[0] = 0xD0;
	for (i = 0; i < 260; i++) {
		di = gsm0610_bitorder[i];
		si = (i > 181) ? i + 4 : i;
		msb_set_bit(outbytes, 4 + di, msb_get_bit(inbytes, si));
        }
}

void
gsm0610_libgsm_to_tidsp(inbytes, outbytes)
	u_char *inbytes, *outbytes;
{
	int i, di, si;

	bzero(outbytes, 33);
	for (i = 0; i < 260; i++) {
		si = gsm0610_bitorder[i];
		di = (i > 181) ? i + 4 : i;
		msb_set_bit(outbytes, di, msb_get_bit(inbytes, 4 + si));
        }
}