| /* |
| * 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 |
| */ |
| #include <pjmedia/alaw_ulaw.h> |
| |
| #if !defined(PJMEDIA_HAS_ALAW_ULAW_TABLE) || PJMEDIA_HAS_ALAW_ULAW_TABLE==0 |
| |
| #ifdef _MSC_VER |
| # pragma warning ( disable: 4244 ) /* Conversion from int to char etc */ |
| #endif |
| |
| /* |
| * 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. */ |
| |
| static short seg_end[8] = {0xFF, 0x1FF, 0x3FF, 0x7FF, |
| 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF}; |
| |
| /* copy from CCITT G.711 specifications */ |
| static 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}; |
| |
| static 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}; |
| |
| static int |
| search( |
| 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. |
| */ |
| PJ_DEF(pj_uint8_t) pjmedia_linear2alaw( |
| 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; |
| |
| /* https://trac.pjsip.org/repos/ticket/1301 |
| * Thank you K Johnson - Zetron - 27 May 2011 |
| */ |
| if (pcm_val < 0) |
| pcm_val = 0; |
| } |
| |
| /* 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 |
| * |
| */ |
| PJ_DEF(int) pjmedia_alaw2linear( |
| unsigned 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. |
| */ |
| PJ_DEF(unsigned char) pjmedia_linear2ulaw( |
| 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. |
| */ |
| PJ_DEF(int) pjmedia_ulaw2linear( |
| unsigned char u_val) |
| { |
| int t; |
| |
| /* Shortcut: when input is zero, output is zero |
| * This will also make the VAD works harder. |
| * -bennylp |
| */ |
| if (u_val == 0) return 0; |
| |
| /* 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; |
| |
| return ((u_val & SIGN_BIT) ? (BIAS - t) : (t - BIAS)); |
| } |
| |
| /* A-law to u-law conversion */ |
| PJ_DEF(unsigned char) pjmedia_alaw2ulaw( |
| unsigned char aval) |
| { |
| aval &= 0xff; |
| return ((aval & 0x80) ? (0xFF ^ _a2u[aval ^ 0xD5]) : |
| (0x7F ^ _a2u[aval ^ 0x55])); |
| } |
| |
| /* u-law to A-law conversion */ |
| PJ_DEF(unsigned char) pjmedia_ulaw2alaw( |
| unsigned char uval) |
| { |
| uval &= 0xff; |
| return ((uval & 0x80) ? (0xD5 ^ (_u2a[0xFF ^ uval] - 1)) : |
| (0x55 ^ (_u2a[0x7F ^ uval] - 1))); |
| } |
| |
| |
| #endif /* PJMEDIA_HAS_ALAW_ULAW_TABLE */ |
| |