/* * G.711.c */ /* All char references need to be altered as sizeof(char)==16bits on DSP for the time being, just return a 16bit variable containing the 8bit data in the bottom half. Eventually this should be changed, either so that the 8bit values are packed, or so that the processing stage takes 2x16bit inputs and returns the 2x8bit in a 16bit variable */ #include #include "mailbox.h" #include "tokliBIOS.h" #define BK_SIZE 256 // this needs to be exactly divisible by two #define HALF_BK_SIZE 128 unsigned char newlinear2ulaw(short int); struct g711_udata { short int *rbuf; unsigned char *wbuf; }; #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 int seg_uend[8] = {0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF}; /* 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, 80, 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}; 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, 80, 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 Uns rcv_bksnd(struct dsptask *task, Uns count) { struct g711_udata *udata = task->udata; short int *input_val; unsigned char *output_val; // use 16bit for the time being, should only use the bottom 8 bits of this variable though unsigned char temp1, temp2; short int count_shorts, i; /* Too much data sent across */ if (count > BK_SIZE*sizeof(short int)) return MBCMD_EID_BADCNT; input_val = (short int *) &(udata->rbuf[0]); output_val = (unsigned char *) &(udata->wbuf[0]); count_shorts = count/2; /* integer divide -> we combine the outputs to simulate an 8bit array */ /* Process the data - only an even number of input shorts (so the output can be constructed without zero padding) */ for(i=0; iwbuf, count_shorts); /* As we've written chars after reading shorts */ /* Request a new input buffer */ bkreqp(task, udata->rbuf, BK_SIZE*sizeof(short int)); return 0; } static Uns rcv_tctl(struct dsptask *task, Uns ctlcmd, Uns *ret, Uns arg) { struct g711_udata *udata = task->udata; switch (ctlcmd) { case MBCMD_TCTL_TINIT: memset(udata->rbuf, 0xbeef, BK_SIZE*sizeof(short int)); memset(udata->wbuf, 0xdead, HALF_BK_SIZE*sizeof(unsigned short int)); bkreqp(task, udata->rbuf, BK_SIZE*sizeof(short int)); return 0; case MBCMD_TCTL_TCLR: case MBCMD_TCTL_TKILL: /* * cleanup code here */ return 0; default: return MBCMD_EID_BADTCTL; } } static short search(short int val, short int *table, short int size) { short int i; for (i = 0; i < size; i++) { if (val <= *table++) return (i); } return (size); } #define BIAS (0x84) /* Bias for linear code. */ #define CLIP 8159 /* * 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 newlinear2ulaw(short int pcm_val) /* 2's complement (16-bit range) */ { short int mask; short int seg; unsigned char uval; /* Get the sign and the magnitude of the value. */ pcm_val = pcm_val >> 2; if (pcm_val < 0) { pcm_val = -pcm_val; mask = 0x7F; } else { mask = 0xFF; } if ( pcm_val > CLIP ) pcm_val = CLIP; /* clip the magnitude */ pcm_val += (BIAS >> 2); /* Convert the scaled magnitude to segment number. */ seg = search(pcm_val, seg_uend, 8); /* * Combine the sign, segment, quantization bits; * and complement the code word. */ if (seg >= 8) /* out of range, return maximum value. */ return (unsigned char) (0x7F ^ mask); else { uval = (unsigned char) (seg << 4) | ((pcm_val >> (seg + 1)) & 0xF); return (uval ^ mask); } } #pragma DATA_SECTION(g711_rbuf_data, "ipbuf"); #pragma DATA_SECTION(g711_wbuf_data, "ipbuf"); static short int g711_rbuf_data[BK_SIZE]; static unsigned char g711_wbuf_data[HALF_BK_SIZE]; static struct g711_udata udata = { g711_rbuf_data, g711_wbuf_data }; #pragma DATA_SECTION(task_g711_ulaw, "dspgw_task") struct dsptask task_g711_ulaw = { TID_MAGIC, /* tid */ "g711_ulaw", /* name */ MBCMD_TTYP_PVDM | MBCMD_TTYP_PVMD | MBCMD_TTYP_BKDM | MBCMD_TTYP_BKMD | MBCMD_TTYP_ASND | MBCMD_TTYP_ARCV, /* ttyp: active block snd, active block rcv */ rcv_bksnd, /* rcv_snd */ NULL, /* rcv_req */ rcv_tctl, /* rcv_tctl */ NULL, /* tsk_attrs */ NULL, /* mmap_info */ &udata /* udata */ };