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/* 
 * This source code is a product of Sun Microsystems, Inc. and is provided 
 * for unrestricted use.  Users may copy or modify this source code without 
 * charge. 
 * 
 * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING 
 * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR 
 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE. 
 * 
 * Sun source code is provided with no support and without any obligation on 
 * the part of Sun Microsystems, Inc. to assist in its use, correction, 
 * modification or enhancement. 
 * 
 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE 
 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE 
 * OR ANY PART THEREOF. 
 * 
 * In no event will Sun Microsystems, Inc. be liable for any lost revenue 
 * or profits or other special, indirect and consequential damages, even if 
 * Sun has been advised of the possibility of such damages. 
 * 
 * Sun Microsystems, Inc. 
 * 2550 Garcia Avenue 
 * Mountain View, California  94043 
 */ 
 
/* 
 * g711.c 
 * 
 * u-law, A-law and linear PCM conversions. 
 */ 
#define SIGN_BIT		(0x80)			/* Sign bit for a A-law byte. */ 
#define QUANT_MASK		(0xf)			/* Quantization field mask. */ 
#define NSEGS			(8) 			/* Number of A-law segments. */ 
#define SEG_SHIFT		(4) 			/* Left shift for segment number. */ 
#define SEG_MASK		(0x70)			/* Segment field mask. */ 
 
#ifdef NEEDED 
 
static short seg_end[8] = {0xFF, 0x1FF, 0x3FF, 0x7FF, 
							0xFFF, 0x1FFF, 0x3FFF, 0x7FFF}; 
 
/* copy from CCITT G.711 specifications */ 
unsigned char _u2a[128] = { 					/* u- to A-law conversions */ 
		1,		1,		2,		2,		3,		3,		4,		4, 
		5,		5,		6,		6,		7,		7,		8,		8, 
		9,		10, 	11, 	12, 	13, 	14, 	15, 	16, 
		17, 	18, 	19, 	20, 	21, 	22, 	23, 	24, 
		25, 	27, 	29, 	31, 	33, 	34, 	35, 	36, 
		37, 	38, 	39, 	40, 	41, 	42, 	43, 	44, 
		46, 	48, 	49, 	50, 	51, 	52, 	53, 	54, 
		55, 	56, 	57, 	58, 	59, 	60, 	61, 	62, 
		64, 	65, 	66, 	67, 	68, 	69, 	70, 	71, 
		72, 	73, 	74, 	75, 	76, 	77, 	78, 	79, 
		81, 	82, 	83, 	84, 	85, 	86, 	87, 	88, 
		89, 	90, 	91, 	92, 	93, 	94, 	95, 	96, 
		97, 	98, 	99, 	100,	101,	102,	103,	104, 
		105,	106,	107,	108,	109,	110,	111,	112, 
		113,	114,	115,	116,	117,	118,	119,	120, 
		121,	122,	123,	124,	125,	126,	127,	128}; 
#endif 
 
unsigned char _a2u[128] = { 					/* A- to u-law conversions */ 
		1,		3,		5,		7,		9,		11, 	13, 	15, 
		16, 	17, 	18, 	19, 	20, 	21, 	22, 	23, 
		24, 	25, 	26, 	27, 	28, 	29, 	30, 	31, 
		32, 	32, 	33, 	33, 	34, 	34, 	35, 	35, 
		36, 	37, 	38, 	39, 	40, 	41, 	42, 	43, 
		44, 	45, 	46, 	47, 	48, 	48, 	49, 	49, 
		50, 	51, 	52, 	53, 	54, 	55, 	56, 	57, 
		58, 	59, 	60, 	61, 	62, 	63, 	64, 	64, 
		65, 	66, 	67, 	68, 	69, 	70, 	71, 	72, 
		73, 	74, 	75, 	76, 	77, 	78, 	79, 	79, 
		80, 	81, 	82, 	83, 	84, 	85, 	86, 	87, 
		88, 	89, 	90, 	91, 	92, 	93, 	94, 	95, 
		96, 	97, 	98, 	99, 	100,	101,	102,	103, 
		104,	105,	106,	107,	108,	109,	110,	111, 
		112,	113,	114,	115,	116,	117,	118,	119, 
		120,	121,	122,	123,	124,	125,	126,	127}; 
 
#ifdef NEEDED 
static int 
search(val, table, size) 
		int 			val; 
		short			*table; 
		int 			size; 
{ 
		int 			i; 
 
		for (i = 0; i < size; i++) { 
				if (val <= *table++) 
						return (i); 
		} 
		return (size); 
} 
 
/* 
 * linear2alaw() - Convert a 16-bit linear PCM value to 8-bit A-law 
 * 
 * linear2alaw() accepts an 16-bit integer and encodes it as A-law data. 
 * 
 *				Linear Input Code		Compressed Code 
 *		------------------------		--------------- 
 *		0000000wxyza					000wxyz 
 *		0000001wxyza					001wxyz 
 *		000001wxyzab					010wxyz 
 *		00001wxyzabc					011wxyz 
 *		0001wxyzabcd					100wxyz 
 *		001wxyzabcde					101wxyz 
 *		01wxyzabcdef					110wxyz 
 *		1wxyzabcdefg					111wxyz 
 * 
 * For further information see John C. Bellamy's Digital Telephony, 1982, 
 * John Wiley & Sons, pps 98-111 and 472-476. 
 */ 
unsigned char 
linear2alaw(pcm_val) 
        int             pcm_val;        /* 2's complement (16-bit range) */ 
{ 
		int 			mask; 
		int 			seg; 
		unsigned char	aval; 
 
		if (pcm_val >= 0) { 
				mask = 0xD5;			/* sign (7th) bit = 1 */ 
		} else { 
				mask = 0x55;			/* sign bit = 0 */ 
				pcm_val = -pcm_val - 8; 
		} 
 
		/* Convert the scaled magnitude to segment number. */ 
		seg = search(pcm_val, seg_end, 8); 
 
		/* Combine the sign, segment, and quantization bits. */ 
 
		if (seg >= 8)			/* out of range, return maximum value. */ 
				return (0x7F ^ mask); 
		else { 
				aval = seg << SEG_SHIFT; 
				if (seg < 2) 
						aval |= (pcm_val >> 4) & QUANT_MASK; 
				else 
						aval |= (pcm_val >> (seg + 3)) & QUANT_MASK; 
				return (aval ^ mask); 
		} 
} 
 
/* 
 * alaw2linear() - Convert an A-law value to 16-bit linear PCM 
 * 
 */ 
int 
alaw2linear(a_val) 
		unsigned char	a_val; 
{ 
		int 			t; 
		int 			seg; 
 
		a_val ^= 0x55; 
 
		t = (a_val & QUANT_MASK) << 4; 
		seg = ((unsigned)a_val & SEG_MASK) >> SEG_SHIFT; 
		switch (seg) { 
		case 0: 
				t += 8; 
				break; 
		case 1: 
				t += 0x108; 
				break; 
		default: 
				t += 0x108; 
				t <<= seg - 1; 
		} 
		return ((a_val & SIGN_BIT) ? t : -t); 
} 
 
#define BIAS			(0x84)			/* Bias for linear code. */ 
 
/* 
 * linear2ulaw() - Convert a linear PCM value to u-law 
 * 
 * In order to simplify the encoding process, the original linear magnitude 
 * is biased by adding 33 which shifts the encoding range from (0 - 8158) to 
 * (33 - 8191). The result can be seen in the following encoding table: 
 * 
 *		Biased Linear Input Code		Compressed Code 
 *		------------------------		--------------- 
 *		00000001wxyza					000wxyz 
 *		0000001wxyzab					001wxyz 
 *		000001wxyzabc					010wxyz 
 *		00001wxyzabcd					011wxyz 
 *		0001wxyzabcde					100wxyz 
 *		001wxyzabcdef					101wxyz 
 *		01wxyzabcdefg					110wxyz 
 *		1wxyzabcdefgh					111wxyz 
 * 
 * Each biased linear code has a leading 1 which identifies the segment 
 * number. The value of the segment number is equal to 7 minus the number 
 * of leading 0's. The quantization interval is directly available as the 
 * four bits wxyz.	* The trailing bits (a - h) are ignored. 
 * 
 * Ordinarily the complement of the resulting code word is used for 
 * transmission, and so the code word is complemented before it is returned. 
 * 
 * For further information see John C. Bellamy's Digital Telephony, 1982, 
 * John Wiley & Sons, pps 98-111 and 472-476. 
 */ 
unsigned char 
linear2ulaw(pcm_val) 
        int             pcm_val;        /* 2's complement (16-bit range) */ 
{ 
		int 			mask; 
		int 			seg; 
		unsigned char	uval; 
 
		/* Get the sign and the magnitude of the value. */ 
		if (pcm_val < 0) { 
				pcm_val = BIAS - pcm_val; 
				mask = 0x7F; 
		} else { 
				pcm_val += BIAS; 
				mask = 0xFF; 
		} 
 
		/* Convert the scaled magnitude to segment number. */ 
		seg = search(pcm_val, seg_end, 8); 
 
		/* 
		 * Combine the sign, segment, quantization bits; 
		 * and complement the code word. 
		 */ 
		if (seg >= 8)			/* out of range, return maximum value. */ 
				return (0x7F ^ mask); 
		else { 
				uval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0xF); 
				return (uval ^ mask); 
		} 
 
} 
 
/* 
 * ulaw2linear() - Convert a u-law value to 16-bit linear PCM 
 * 
 * First, a biased linear code is derived from the code word. An unbiased 
 * output can then be obtained by subtracting 33 from the biased code. 
 * 
 * Note that this function expects to be passed the complement of the 
 * original code word. This is in keeping with ISDN conventions. 
 */ 
int 
ulaw2linear(u_val) 
		unsigned char	u_val; 
{ 
		int 			t; 
 
		/* Complement to obtain normal u-law value. */ 
		u_val = ~u_val; 
 
		/* 
		 * Extract and bias the quantization bits. Then 
		 * shift up by the segment number and subtract out the bias. 
		 */ 
		t = ((u_val & QUANT_MASK) << 3) + BIAS; 
		t <<= ((unsigned)u_val & SEG_MASK) >> SEG_SHIFT; 
ed s 
		return ((u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS)); 
} 
#endif 
 
/* A-law to u-law conversion */ 
unsigned char 
alaw2ulaw(aval) 
		unsigned char	aval; 
{ 
		aval &= 0xff; 
		return ((aval & 0x80) ? (0xFF ^ _a2u[aval ^ 0xD5]) : 
			(0x7F ^ _a2u[aval ^ 0x55])); 
} 
 
#ifdef NEEDED 
/* u-law to A-law conversion */ 
unsigned char 
ulaw2alaw(uval) 
		unsigned char	uval; 
{ 
		uval &= 0xff; 
		return ((uval & 0x80) ? (0xD5 ^ (_u2a[0xFF ^ uval] - 1)) : 
			(0x55 ^ (_u2a[0x7F ^ uval] - 1))); 
} 
#endif