/* * PCM - A-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 (*alaw_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; alaw_f func; int sformat; int cformat; int cxfer_mode, cmmap_shape; } snd_pcm_alaw_t; static inline int val_seg(int val) { int r = 1; val >>= 8; if (val & 0xf0) { val >>= 4; r += 4; } if (val & 0x0c) { val >>= 2; r += 2; } if (val & 0x02) r += 1; return r; } /* * s16_to_alaw() - Convert a 16-bit linear PCM value to 8-bit A-law * * s16_to_alaw() 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. */ static unsigned char s16_to_alaw(int pcm_val) { int mask; int seg; unsigned char aval; if (pcm_val >= 0) { mask = 0xD5; } else { mask = 0x55; pcm_val = -pcm_val; if (pcm_val > 0x7fff) pcm_val = 0x7fff; } if (pcm_val < 256) aval = pcm_val >> 4; else { /* Convert the scaled magnitude to segment number. */ seg = val_seg(pcm_val); aval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0x0f); } return aval ^ mask; } /* * alaw_to_s16() - Convert an A-law value to 16-bit linear PCM * */ static int alaw_to_s16(unsigned char a_val) { int t; int seg; a_val ^= 0x55; t = a_val & 0x7f; if (t < 16) t = (t << 4) + 8; else { seg = (t >> 4) & 0x07; t = ((t & 0x0f) << 4) + 0x108; t <<= seg -1; } return ((a_val & 0x80) ? t : -t); } static void alaw_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 PUT_S16_LABELS #include "plugin_ops.h" #undef PUT_S16_LABELS void *put = put_s16_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 = alaw_to_s16(*src); goto *put; #define PUT_S16_END after #include "plugin_ops.h" #undef PUT_S16_END after: src += src_step; dst += dst_step; } } } static void alaw_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 GET_S16_LABELS #include "plugin_ops.h" #undef GET_S16_LABELS void *get = get_s16_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 GET_S16_END after #include "plugin_ops.h" #undef GET_S16_END after: *dst = s16_to_alaw(sample); src += src_step; dst += dst_step; } } } static int snd_pcm_alaw_params_info(snd_pcm_t *pcm, snd_pcm_params_info_t * info) { snd_pcm_alaw_t *alaw = pcm->private; unsigned int req_mask = info->req_mask; unsigned int sfmt = info->req.format.sfmt; int err; if (req_mask & SND_PCM_PARAMS_SFMT) { if (alaw->sformat == SND_PCM_SFMT_A_LAW ? !snd_pcm_format_linear(sfmt) : sfmt != SND_PCM_SFMT_A_LAW) { info->req.fail_mask = SND_PCM_PARAMS_SFMT; info->req.fail_reason = SND_PCM_PARAMS_FAIL_INVAL; return -EINVAL; } } info->req_mask |= SND_PCM_PARAMS_SFMT; info->req_mask &= ~(SND_PCM_PARAMS_MMAP_SHAPE | SND_PCM_PARAMS_XFER_MODE); info->req.format.sfmt = alaw->sformat; err = snd_pcm_params_info(alaw->plug.slave, info); info->req_mask = req_mask; info->req.format.sfmt = sfmt; if (err < 0) return err; if (req_mask & SND_PCM_PARAMS_SFMT) info->formats = 1 << sfmt; else info->formats = alaw->sformat == SND_PCM_SFMT_A_LAW ? SND_PCM_LINEAR_FORMATS : 1 << SND_PCM_SFMT_A_LAW; info->flags &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID); info->flags |= SND_PCM_INFO_INTERLEAVED | SND_PCM_INFO_NONINTERLEAVED; return err; } static int snd_pcm_alaw_params(snd_pcm_t *pcm, snd_pcm_params_t * params) { snd_pcm_alaw_t *alaw = pcm->private; snd_pcm_t *slave = alaw->plug.slave; int err; if (alaw->sformat == SND_PCM_SFMT_A_LAW ? !snd_pcm_format_linear(params->format.sfmt) : params->format.sfmt != SND_PCM_SFMT_A_LAW) { params->fail_mask = SND_PCM_PARAMS_SFMT; params->fail_reason = SND_PCM_PARAMS_FAIL_INVAL; return -EINVAL; } if (slave->mmap_data) { err = snd_pcm_munmap_data(slave); if (err < 0) return err; } alaw->cformat = params->format.sfmt; alaw->cxfer_mode = params->xfer_mode; alaw->cmmap_shape = params->mmap_shape; params->format.sfmt = alaw->sformat; params->xfer_mode = SND_PCM_XFER_UNSPECIFIED; params->mmap_shape = SND_PCM_MMAP_UNSPECIFIED;; err = snd_pcm_params(slave, params); params->format.sfmt = alaw->cformat; params->xfer_mode = alaw->cxfer_mode; params->mmap_shape = alaw->cmmap_shape; if (slave->valid_setup) { int r = snd_pcm_mmap_data(slave, NULL); assert(r >= 0); } return err; } static int snd_pcm_alaw_setup(snd_pcm_t *pcm, snd_pcm_setup_t * setup) { snd_pcm_alaw_t *alaw = pcm->private; int err = snd_pcm_setup(alaw->plug.slave, setup); if (err < 0) return err; assert(alaw->sformat == setup->format.sfmt); if (alaw->cxfer_mode == SND_PCM_XFER_UNSPECIFIED) setup->xfer_mode = SND_PCM_XFER_NONINTERLEAVED; else setup->xfer_mode = alaw->cxfer_mode; if (alaw->cmmap_shape == SND_PCM_MMAP_UNSPECIFIED) setup->mmap_shape = SND_PCM_MMAP_NONINTERLEAVED; else setup->mmap_shape = alaw->cmmap_shape; setup->format.sfmt = alaw->cformat; setup->mmap_bytes = 0; if (pcm->stream == SND_PCM_STREAM_PLAYBACK) { if (alaw->sformat == SND_PCM_SFMT_A_LAW) { alaw->getput_idx = getput_index(alaw->cformat); alaw->func = alaw_encode; } else { alaw->getput_idx = getput_index(alaw->sformat); alaw->func = alaw_decode; } } else { if (alaw->sformat == SND_PCM_SFMT_A_LAW) { alaw->getput_idx = getput_index(alaw->cformat); alaw->func = alaw_decode; } else { alaw->getput_idx = getput_index(alaw->sformat); alaw->func = alaw_encode; } } return 0; } static ssize_t snd_pcm_alaw_write_areas(snd_pcm_t *pcm, snd_pcm_channel_area_t *areas, size_t offset, size_t size, size_t *slave_sizep) { snd_pcm_alaw_t *alaw = pcm->private; snd_pcm_t *slave = alaw->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); alaw->func(areas, offset, snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave), frames, pcm->setup.format.channels, alaw->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_alaw_read_areas(snd_pcm_t *pcm, snd_pcm_channel_area_t *areas, size_t offset, size_t size, size_t *slave_sizep) { snd_pcm_alaw_t *alaw = pcm->private; snd_pcm_t *slave = alaw->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); alaw->func(snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave), areas, offset, frames, pcm->setup.format.channels, alaw->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_alaw_dump(snd_pcm_t *pcm, FILE *fp) { snd_pcm_alaw_t *alaw = pcm->private; fprintf(fp, "A-Law conversion PCM (%s)\n", snd_pcm_format_name(alaw->sformat)); if (pcm->valid_setup) { fprintf(fp, "Its setup is:\n"); snd_pcm_dump_setup(pcm, fp); } fprintf(fp, "Slave: "); snd_pcm_dump(alaw->plug.slave, fp); } struct snd_pcm_ops snd_pcm_alaw_ops = { close: snd_pcm_plugin_close, info: snd_pcm_plugin_info, params_info: snd_pcm_alaw_params_info, params: snd_pcm_alaw_params, setup: snd_pcm_alaw_setup, channel_info: snd_pcm_plugin_channel_info, channel_params: snd_pcm_plugin_channel_params, channel_setup: snd_pcm_plugin_channel_setup, dump: snd_pcm_alaw_dump, nonblock: snd_pcm_plugin_nonblock, async: snd_pcm_plugin_async, mmap_status: snd_pcm_plugin_mmap_status, mmap_control: snd_pcm_plugin_mmap_control, mmap_data: snd_pcm_plugin_mmap_data, munmap_status: snd_pcm_plugin_munmap_status, munmap_control: snd_pcm_plugin_munmap_control, munmap_data: snd_pcm_plugin_munmap_data, }; int snd_pcm_alaw_open(snd_pcm_t **handlep, char *name, int sformat, snd_pcm_t *slave, int close_slave) { snd_pcm_t *handle; snd_pcm_alaw_t *alaw; int err; assert(handlep && slave); if (snd_pcm_format_linear(sformat) != 1 && sformat != SND_PCM_SFMT_A_LAW) return -EINVAL; alaw = calloc(1, sizeof(snd_pcm_alaw_t)); if (!alaw) { return -ENOMEM; } alaw->sformat = sformat; alaw->plug.read = snd_pcm_alaw_read_areas; alaw->plug.write = snd_pcm_alaw_write_areas; alaw->plug.slave = slave; alaw->plug.close_slave = close_slave; handle = calloc(1, sizeof(snd_pcm_t)); if (!handle) { free(alaw); return -ENOMEM; } if (name) handle->name = strdup(name); handle->type = SND_PCM_TYPE_ALAW; handle->stream = slave->stream; handle->ops = &snd_pcm_alaw_ops; handle->op_arg = handle; handle->fast_ops = &snd_pcm_plugin_fast_ops; handle->fast_op_arg = handle; handle->mode = slave->mode; handle->private = alaw; err = snd_pcm_init(handle); if (err < 0) { snd_pcm_close(handle); return err; } *handlep = handle; return 0; } int _snd_pcm_alaw_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) return -EINVAL; continue; } if (strcmp(n->id, "sformat") == 0) { char *f; err = snd_config_string_get(n, &f); if (err < 0) return -EINVAL; sformat = snd_pcm_format_value(f); if (sformat < 0) return -EINVAL; if (snd_pcm_format_linear(sformat) != 1 && sformat != SND_PCM_SFMT_A_LAW) return -EINVAL; continue; } return -EINVAL; } if (!sname || !sformat) 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_alaw_open(pcmp, name, sformat, spcm, 1); if (err < 0) snd_pcm_close(spcm); return err; }