/* * PCM - Mu-Law conversion * Copyright (c) 2000 by Abramo Bagnara * * * This library is free software; you can redistribute it and/or modify * it under the terms of the GNU Library General Public License as * published by the Free Software Foundation; either version 2 of * the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * */ #include #include "pcm_local.h" #include "pcm_plugin.h" typedef void (*mulaw_f)(snd_pcm_channel_area_t *src_areas, size_t src_offset, snd_pcm_channel_area_t *dst_areas, size_t dst_offset, size_t frames, size_t channels, int getputidx); typedef struct { /* This field need to be the first */ snd_pcm_plugin_t plug; int getput_idx; mulaw_f func; int sformat; } snd_pcm_mulaw_t; static inline int val_seg(int val) { int r = 0; val >>= 7; if (val & 0xf0) { val >>= 4; r += 4; } if (val & 0x0c) { val >>= 2; r += 2; } if (val & 0x02) r += 1; return r; } /* * s16_to_ulaw() - 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. */ static unsigned char s16_to_ulaw(int pcm_val) /* 2's complement (16-bit range) */ { int mask; int seg; unsigned char uval; if (pcm_val < 0) { pcm_val = -pcm_val + 0x84; mask = 0x7f; } else { pcm_val += 0x84; mask = 0xff; } if (pcm_val > 0x7fff) pcm_val = 0x7fff; /* Convert the scaled magnitude to segment number. */ seg = val_seg(pcm_val); /* * Combine the sign, segment, quantization bits; * and complement the code word. */ uval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0x0f); return uval ^ mask; } /* * ulaw_to_s16() - 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. */ static int ulaw_to_s16(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 & 0x0f) << 3) + 0x84; t <<= (u_val & 0x70) >> 4; return ((u_val & 0x80) ? (0x84 - t) : (t - 0x84)); } static void mulaw_decode(snd_pcm_channel_area_t *src_areas, size_t src_offset, snd_pcm_channel_area_t *dst_areas, size_t dst_offset, size_t frames, size_t channels, int putidx) { #define PUT16_LABELS #include "plugin_ops.h" #undef PUT16_LABELS void *put = put16_labels[putidx]; size_t channel; for (channel = 0; channel < channels; ++channel) { char *src; char *dst; int src_step, dst_step; size_t frames1; snd_pcm_channel_area_t *src_area = &src_areas[channel]; snd_pcm_channel_area_t *dst_area = &dst_areas[channel]; #if 0 if (!src_area->enabled) { if (dst_area->wanted) snd_pcm_area_silence(&dst_areas[channel], dst_offset, frames, dst_sfmt); dst_area->enabled = 0; continue; } dst_area->enabled = 1; #endif src = snd_pcm_channel_area_addr(src_area, src_offset); dst = snd_pcm_channel_area_addr(dst_area, dst_offset); src_step = snd_pcm_channel_area_step(src_area); dst_step = snd_pcm_channel_area_step(dst_area); frames1 = frames; while (frames1-- > 0) { int16_t sample = ulaw_to_s16(*src); goto *put; #define PUT16_END after #include "plugin_ops.h" #undef PUT16_END after: src += src_step; dst += dst_step; } } } static void mulaw_encode(snd_pcm_channel_area_t *src_areas, size_t src_offset, snd_pcm_channel_area_t *dst_areas, size_t dst_offset, size_t frames, size_t channels, int getidx) { #define GET16_LABELS #include "plugin_ops.h" #undef GET16_LABELS void *get = get16_labels[getidx]; size_t channel; int16_t sample = 0; for (channel = 0; channel < channels; ++channel) { char *src; char *dst; int src_step, dst_step; size_t frames1; snd_pcm_channel_area_t *src_area = &src_areas[channel]; snd_pcm_channel_area_t *dst_area = &dst_areas[channel]; #if 0 if (!src_area->enabled) { if (dst_area->wanted) snd_pcm_area_silence(&dst_area->area, 0, frames, dst_sfmt); dst_area->enabled = 0; continue; } dst_area->enabled = 1; #endif src = snd_pcm_channel_area_addr(src_area, src_offset); dst = snd_pcm_channel_area_addr(dst_area, dst_offset); src_step = snd_pcm_channel_area_step(src_area); dst_step = snd_pcm_channel_area_step(dst_area); frames1 = frames; while (frames1-- > 0) { goto *get; #define GET16_END after #include "plugin_ops.h" #undef GET16_END after: *dst = s16_to_ulaw(sample); src += src_step; dst += dst_step; } } } static int snd_pcm_mulaw_hw_info(snd_pcm_t *pcm, snd_pcm_hw_info_t * info) { snd_pcm_mulaw_t *mulaw = pcm->private; unsigned int format_mask, access_mask; int err; info->access_mask &= (SND_PCM_ACCBIT_MMAP_INTERLEAVED | SND_PCM_ACCBIT_RW_INTERLEAVED | SND_PCM_ACCBIT_MMAP_NONINTERLEAVED | SND_PCM_ACCBIT_RW_NONINTERLEAVED); access_mask = info->access_mask; if (access_mask == 0) return -EINVAL; if (mulaw->sformat == SND_PCM_FORMAT_MU_LAW) info->format_mask &= SND_PCM_FMTBIT_LINEAR; else info->format_mask &= SND_PCM_FMTBIT_MU_LAW; format_mask = info->format_mask; if (format_mask == 0) return -EINVAL; info->format_mask = 1U << mulaw->sformat; info->access_mask = SND_PCM_ACCBIT_MMAP; err = snd_pcm_hw_info(mulaw->plug.slave, info); info->format_mask = format_mask; info->access_mask = access_mask; if (err < 0) return err; info->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID); snd_pcm_hw_info_complete(info); return 0; } static int snd_pcm_mulaw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params) { snd_pcm_mulaw_t *mulaw = pcm->private; snd_pcm_t *slave = mulaw->plug.slave; snd_pcm_hw_info_t sinfo; snd_pcm_hw_params_t sparams; int err; snd_pcm_hw_params_to_info(params, &sinfo); sinfo.format_mask = 1 << mulaw->sformat; sinfo.access_mask = SND_PCM_ACCBIT_MMAP; err = snd_pcm_hw_params_info(slave, &sparams, &sinfo); params->fail_mask = sparams.fail_mask; if (err < 0) return err; if (pcm->stream == SND_PCM_STREAM_PLAYBACK) { if (mulaw->sformat == SND_PCM_FORMAT_MU_LAW) { mulaw->getput_idx = get_index(params->format, SND_PCM_FORMAT_S16); mulaw->func = mulaw_encode; } else { mulaw->getput_idx = put_index(SND_PCM_FORMAT_S16, mulaw->sformat); mulaw->func = mulaw_decode; } } else { if (mulaw->sformat == SND_PCM_FORMAT_MU_LAW) { mulaw->getput_idx = put_index(SND_PCM_FORMAT_S16, params->format); mulaw->func = mulaw_decode; } else { mulaw->getput_idx = get_index(mulaw->sformat, SND_PCM_FORMAT_S16); mulaw->func = mulaw_encode; } } return 0; } static ssize_t snd_pcm_mulaw_write_areas(snd_pcm_t *pcm, snd_pcm_channel_area_t *areas, size_t offset, size_t size, size_t *slave_sizep) { snd_pcm_mulaw_t *mulaw = pcm->private; snd_pcm_t *slave = mulaw->plug.slave; size_t xfer = 0; ssize_t err = 0; if (slave_sizep && *slave_sizep < size) size = *slave_sizep; assert(size > 0); while (xfer < size) { size_t frames = snd_pcm_mmap_playback_xfer(slave, size - xfer); mulaw->func(areas, offset, snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave), frames, pcm->channels, mulaw->getput_idx); err = snd_pcm_mmap_forward(slave, frames); if (err < 0) break; assert((size_t)err == frames); offset += err; xfer += err; snd_pcm_mmap_hw_forward(pcm, err); } if (xfer > 0) { if (slave_sizep) *slave_sizep = xfer; return xfer; } return err; } static ssize_t snd_pcm_mulaw_read_areas(snd_pcm_t *pcm, snd_pcm_channel_area_t *areas, size_t offset, size_t size, size_t *slave_sizep) { snd_pcm_mulaw_t *mulaw = pcm->private; snd_pcm_t *slave = mulaw->plug.slave; size_t xfer = 0; ssize_t err = 0; if (slave_sizep && *slave_sizep < size) size = *slave_sizep; assert(size > 0); while (xfer < size) { size_t frames = snd_pcm_mmap_capture_xfer(slave, size - xfer); mulaw->func(snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave), areas, offset, frames, pcm->channels, mulaw->getput_idx); err = snd_pcm_mmap_forward(slave, frames); if (err < 0) break; assert((size_t)err == frames); offset += err; xfer += err; snd_pcm_mmap_hw_forward(pcm, err); } if (xfer > 0) { if (slave_sizep) *slave_sizep = xfer; return xfer; } return err; } static void snd_pcm_mulaw_dump(snd_pcm_t *pcm, FILE *fp) { snd_pcm_mulaw_t *mulaw = pcm->private; fprintf(fp, "Mu-Law conversion PCM (%s)\n", snd_pcm_format_name(mulaw->sformat)); if (pcm->setup) { fprintf(fp, "Its setup is:\n"); snd_pcm_dump_setup(pcm, fp); } fprintf(fp, "Slave: "); snd_pcm_dump(mulaw->plug.slave, fp); } snd_pcm_ops_t snd_pcm_mulaw_ops = { close: snd_pcm_plugin_close, info: snd_pcm_plugin_info, hw_info: snd_pcm_mulaw_hw_info, hw_params: snd_pcm_mulaw_hw_params, sw_params: snd_pcm_plugin_sw_params, dig_info: snd_pcm_plugin_dig_info, dig_params: snd_pcm_plugin_dig_params, channel_info: snd_pcm_plugin_channel_info, dump: snd_pcm_mulaw_dump, nonblock: snd_pcm_plugin_nonblock, async: snd_pcm_plugin_async, mmap: snd_pcm_plugin_mmap, munmap: snd_pcm_plugin_munmap, }; int snd_pcm_mulaw_open(snd_pcm_t **pcmp, char *name, int sformat, snd_pcm_t *slave, int close_slave) { snd_pcm_t *pcm; snd_pcm_mulaw_t *mulaw; assert(pcmp && slave); if (snd_pcm_format_linear(sformat) != 1 && sformat != SND_PCM_FORMAT_MU_LAW) return -EINVAL; mulaw = calloc(1, sizeof(snd_pcm_mulaw_t)); if (!mulaw) { return -ENOMEM; } mulaw->sformat = sformat; mulaw->plug.read = snd_pcm_mulaw_read_areas; mulaw->plug.write = snd_pcm_mulaw_write_areas; mulaw->plug.slave = slave; mulaw->plug.close_slave = close_slave; pcm = calloc(1, sizeof(snd_pcm_t)); if (!pcm) { free(mulaw); return -ENOMEM; } if (name) pcm->name = strdup(name); pcm->type = SND_PCM_TYPE_MULAW; pcm->stream = slave->stream; pcm->mode = slave->mode; pcm->ops = &snd_pcm_mulaw_ops; pcm->op_arg = pcm; pcm->fast_ops = &snd_pcm_plugin_fast_ops; pcm->fast_op_arg = pcm; pcm->private = mulaw; pcm->poll_fd = slave->poll_fd; pcm->hw_ptr = &mulaw->plug.hw_ptr; pcm->appl_ptr = &mulaw->plug.appl_ptr; *pcmp = pcm; return 0; } int _snd_pcm_mulaw_open(snd_pcm_t **pcmp, char *name, snd_config_t *conf, int stream, int mode) { snd_config_iterator_t i; char *sname = NULL; int err; snd_pcm_t *spcm; int sformat = -1; snd_config_foreach(i, conf) { snd_config_t *n = snd_config_entry(i); if (strcmp(n->id, "comment") == 0) continue; if (strcmp(n->id, "type") == 0) continue; if (strcmp(n->id, "stream") == 0) continue; if (strcmp(n->id, "sname") == 0) { err = snd_config_string_get(n, &sname); if (err < 0) { ERR("Invalid type for %s", n->id); return -EINVAL; } continue; } if (strcmp(n->id, "sformat") == 0) { char *f; err = snd_config_string_get(n, &f); if (err < 0) { ERR("Invalid type for %s", n->id); return -EINVAL; } sformat = snd_pcm_format_value(f); if (sformat < 0) { ERR("Unknown sformat"); return -EINVAL; } if (snd_pcm_format_linear(sformat) != 1 && sformat != SND_PCM_FORMAT_MU_LAW) { ERR("Invalid sformat"); return -EINVAL; } continue; } ERR("Unknown field %s", n->id); return -EINVAL; } if (!sname) { ERR("sname is not defined"); return -EINVAL; } if (sformat < 0) { ERR("sformat is not defined"); return -EINVAL; } /* This is needed cause snd_config_update may destroy config */ sname = strdup(sname); if (!sname) return -ENOMEM; err = snd_pcm_open(&spcm, sname, stream, mode); free(sname); if (err < 0) return err; err = snd_pcm_mulaw_open(pcmp, name, sformat, spcm, 1); if (err < 0) snd_pcm_close(spcm); return err; }