FreeCalypso > hg > gsm-codec-lib
view libgsmfr2/comfort_noise.c @ 507:06578223a752
libgsmhr1: integrate sp_rom.c
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Wed, 19 Jun 2024 02:13:56 +0000 |
parents | 573afa985df6 |
children |
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/* * In this module we implement comfort noise generation per GSM 06.12 * or 3GPP TS 46.012. */ #include <stdint.h> #include <string.h> #include "tw_gsmfr.h" #include "pp_state.h" #include "pp_internal.h" static const uint8_t fold_table_8to6[24] = { 1, 2, 3, 4, 5, 6, 1, 2, 1, 2, 3, 4, 5, 6, 3, 4, 1, 2, 3, 4, 5, 6, 5, 6, }; static const uint8_t bc[4] = {0, 0, 0, 0}; static const uint8_t Nc[4] = {40, 120, 40, 120}; static uint8_t random_1to6(struct gsmfr_preproc_state *st) { uint8_t range8, range6; range8 = gsmfr_preproc_prng(st, 3); range6 = fold_table_8to6[(st->cn_random_6fold << 3) | range8]; st->cn_random_6fold++; if (st->cn_random_6fold >= 3) st->cn_random_6fold = 0; return range6; } void gsmfr_preproc_gen_cn(struct gsmfr_preproc_state *st, uint8_t *frame) { unsigned sub, pulse; uint8_t Mc, xmc[13]; uint8_t *c; /* global bytes (magic and LARc) are fixed */ memcpy(frame, st->sid_prefix, 5); c = frame + 5; /* now do the 4 subframes, mostly PRNG output */ for (sub = 0; sub < 4; sub++) { Mc = gsmfr_preproc_prng(st, 2); for (pulse = 0; pulse < 13; pulse++) xmc[pulse] = random_1to6(st); /* packing code from libgsm */ *c++ = ((Nc[sub] & 0x7F) << 1) | ((bc[sub] >> 1) & 0x1); *c++ = ((bc[sub] & 0x1) << 7) | ((Mc & 0x3) << 5) | ((st->sid_xmaxc >> 1) & 0x1F); *c++ = ((st->sid_xmaxc & 0x1) << 7) | ((xmc[0] & 0x7) << 4) | ((xmc[1] & 0x7) << 1) | ((xmc[2] >> 2) & 0x1); *c++ = ((xmc[2] & 0x3) << 6) | ((xmc[3] & 0x7) << 3) | (xmc[4] & 0x7); *c++ = ((xmc[5] & 0x7) << 5) | ((xmc[6] & 0x7) << 2) | ((xmc[7] >> 1) & 0x3); *c++ = ((xmc[7] & 0x1) << 7) | ((xmc[8] & 0x7) << 4) | ((xmc[9] & 0x7) << 1) | ((xmc[10] >> 2) & 0x1); *c++ = ((xmc[10] & 0x3) << 6) | ((xmc[11] & 0x7) << 3) | (xmc[12] & 0x7); } } void gsmfr_preproc_sid2cn(struct gsmfr_preproc_state *st, uint8_t *frame) { unsigned sub, pulse; uint8_t Mc, xmc[13]; uint8_t *c; /* save LARc and Xmaxc from the last subframe for subsequent CN gen */ memcpy(st->sid_prefix, frame, 5); st->sid_xmaxc = ((frame[27] & 0x1F) << 1) | (frame[28] >> 7); /* ... and turn *this* frame into very first CN output */ c = frame + 5; for (sub = 0; sub < 4; sub++) { Mc = gsmfr_preproc_prng(st, 2); for (pulse = 0; pulse < 13; pulse++) xmc[pulse] = random_1to6(st); /* keep each of Xmaxc and replace the rest with CN */ *c++ = ((Nc[sub] & 0x7F) << 1) | ((bc[sub] >> 1) & 0x1); *c &= 0x1F; *c++ |= ((bc[sub] & 0x1) << 7) | ((Mc & 0x3) << 5); *c &= 0x80; *c++ |= ((xmc[0] & 0x7) << 4) | ((xmc[1] & 0x7) << 1) | ((xmc[2] >> 2) & 0x1); *c++ = ((xmc[2] & 0x3) << 6) | ((xmc[3] & 0x7) << 3) | (xmc[4] & 0x7); *c++ = ((xmc[5] & 0x7) << 5) | ((xmc[6] & 0x7) << 2) | ((xmc[7] >> 1) & 0x3); *c++ = ((xmc[7] & 0x1) << 7) | ((xmc[8] & 0x7) << 4) | ((xmc[9] & 0x7) << 1) | ((xmc[10] >> 2) & 0x1); *c++ = ((xmc[10] & 0x3) << 6) | ((xmc[11] & 0x7) << 3) | (xmc[12] & 0x7); } }