/** * \file pcm/pcm_alaw.c * \ingroup PCM_Plugins * \brief PCM A-Law Conversion Plugin Interface * \author Abramo Bagnara * \date 2000-2001 */ /* * 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 Lesser General Public License as * published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * */ #include "bswap.h" #include "pcm_local.h" #include "pcm_plugin.h" #include "plugin_ops.h" #ifndef PIC /* entry for static linking */ const char *_snd_module_pcm_alaw = ""; #endif #ifndef DOC_HIDDEN typedef void (*alaw_f)(const snd_pcm_channel_area_t *dst_areas, snd_pcm_uframes_t dst_offset, const snd_pcm_channel_area_t *src_areas, snd_pcm_uframes_t src_offset, unsigned int channels, snd_pcm_uframes_t frames, unsigned int getputidx); typedef struct { /* This field need to be the first */ snd_pcm_plugin_t plug; unsigned int getput_idx; alaw_f func; snd_pcm_format_t sformat; } snd_pcm_alaw_t; #endif 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); } #ifndef DOC_HIDDEN void snd_pcm_alaw_decode(const snd_pcm_channel_area_t *dst_areas, snd_pcm_uframes_t dst_offset, const snd_pcm_channel_area_t *src_areas, snd_pcm_uframes_t src_offset, unsigned int channels, snd_pcm_uframes_t frames, unsigned int putidx) { #define PUT16_LABELS #include "plugin_ops.h" #undef PUT16_LABELS void *put = put16_labels[putidx]; unsigned int channel; for (channel = 0; channel < channels; ++channel) { const unsigned char *src; char *dst; int src_step, dst_step; snd_pcm_uframes_t frames1; const snd_pcm_channel_area_t *src_area = &src_areas[channel]; const snd_pcm_channel_area_t *dst_area = &dst_areas[channel]; 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 PUT16_END after #include "plugin_ops.h" #undef PUT16_END after: src += src_step; dst += dst_step; } } } void snd_pcm_alaw_encode(const snd_pcm_channel_area_t *dst_areas, snd_pcm_uframes_t dst_offset, const snd_pcm_channel_area_t *src_areas, snd_pcm_uframes_t src_offset, unsigned int channels, snd_pcm_uframes_t frames, unsigned int getidx) { #define GET16_LABELS #include "plugin_ops.h" #undef GET16_LABELS void *get = get16_labels[getidx]; unsigned int channel; int16_t sample = 0; for (channel = 0; channel < channels; ++channel) { const char *src; char *dst; int src_step, dst_step; snd_pcm_uframes_t frames1; const snd_pcm_channel_area_t *src_area = &src_areas[channel]; const snd_pcm_channel_area_t *dst_area = &dst_areas[channel]; 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_alaw(sample); src += src_step; dst += dst_step; } } } #endif /* DOC_HIDDEN */ static int snd_pcm_alaw_hw_refine_cprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *params) { snd_pcm_alaw_t *alaw = pcm->private_data; int err; snd_pcm_access_mask_t access_mask = { SND_PCM_ACCBIT_SHM }; err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_ACCESS, &access_mask); if (err < 0) return err; if (alaw->sformat == SND_PCM_FORMAT_A_LAW) { snd_pcm_format_mask_t format_mask = { SND_PCM_FMTBIT_LINEAR }; err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_FORMAT, &format_mask); } else { err = _snd_pcm_hw_params_set_format(params, SND_PCM_FORMAT_A_LAW); } if (err < 0) return err; err = _snd_pcm_hw_params_set_subformat(params, SND_PCM_SUBFORMAT_STD); if (err < 0) return err; params->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID); return 0; } static int snd_pcm_alaw_hw_refine_sprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *sparams) { snd_pcm_alaw_t *alaw = pcm->private_data; snd_pcm_access_mask_t saccess_mask = { SND_PCM_ACCBIT_MMAP }; _snd_pcm_hw_params_any(sparams); _snd_pcm_hw_param_set_mask(sparams, SND_PCM_HW_PARAM_ACCESS, &saccess_mask); _snd_pcm_hw_params_set_format(sparams, alaw->sformat); _snd_pcm_hw_params_set_subformat(sparams, SND_PCM_SUBFORMAT_STD); return 0; } static int snd_pcm_alaw_hw_refine_schange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params, snd_pcm_hw_params_t *sparams) { int err; unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS | SND_PCM_HW_PARBIT_RATE | SND_PCM_HW_PARBIT_PERIOD_SIZE | SND_PCM_HW_PARBIT_BUFFER_SIZE | SND_PCM_HW_PARBIT_PERIODS | SND_PCM_HW_PARBIT_PERIOD_TIME | SND_PCM_HW_PARBIT_BUFFER_TIME | SND_PCM_HW_PARBIT_TICK_TIME); err = _snd_pcm_hw_params_refine(sparams, links, params); if (err < 0) return err; return 0; } static int snd_pcm_alaw_hw_refine_cchange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params, snd_pcm_hw_params_t *sparams) { int err; unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS | SND_PCM_HW_PARBIT_RATE | SND_PCM_HW_PARBIT_PERIOD_SIZE | SND_PCM_HW_PARBIT_BUFFER_SIZE | SND_PCM_HW_PARBIT_PERIODS | SND_PCM_HW_PARBIT_PERIOD_TIME | SND_PCM_HW_PARBIT_BUFFER_TIME | SND_PCM_HW_PARBIT_TICK_TIME); err = _snd_pcm_hw_params_refine(params, links, sparams); if (err < 0) return err; return 0; } static int snd_pcm_alaw_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params) { return snd_pcm_hw_refine_slave(pcm, params, snd_pcm_alaw_hw_refine_cprepare, snd_pcm_alaw_hw_refine_cchange, snd_pcm_alaw_hw_refine_sprepare, snd_pcm_alaw_hw_refine_schange, snd_pcm_generic_hw_refine); } static int snd_pcm_alaw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params) { snd_pcm_alaw_t *alaw = pcm->private_data; snd_pcm_format_t format; int err = snd_pcm_hw_params_slave(pcm, params, snd_pcm_alaw_hw_refine_cchange, snd_pcm_alaw_hw_refine_sprepare, snd_pcm_alaw_hw_refine_schange, snd_pcm_generic_hw_params); if (err < 0) return err; err = INTERNAL(snd_pcm_hw_params_get_format)(params, &format); if (err < 0) return err; if (pcm->stream == SND_PCM_STREAM_PLAYBACK) { if (alaw->sformat == SND_PCM_FORMAT_A_LAW) { alaw->getput_idx = snd_pcm_linear_get_index(format, SND_PCM_FORMAT_S16); alaw->func = snd_pcm_alaw_encode; } else { alaw->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, alaw->sformat); alaw->func = snd_pcm_alaw_decode; } } else { if (alaw->sformat == SND_PCM_FORMAT_A_LAW) { alaw->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, format); alaw->func = snd_pcm_alaw_decode; } else { alaw->getput_idx = snd_pcm_linear_get_index(alaw->sformat, SND_PCM_FORMAT_S16); alaw->func = snd_pcm_alaw_encode; } } return 0; } static snd_pcm_uframes_t snd_pcm_alaw_write_areas(snd_pcm_t *pcm, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size, const snd_pcm_channel_area_t *slave_areas, snd_pcm_uframes_t slave_offset, snd_pcm_uframes_t *slave_sizep) { snd_pcm_alaw_t *alaw = pcm->private_data; if (size > *slave_sizep) size = *slave_sizep; alaw->func(slave_areas, slave_offset, areas, offset, pcm->channels, size, alaw->getput_idx); *slave_sizep = size; return size; } static snd_pcm_uframes_t snd_pcm_alaw_read_areas(snd_pcm_t *pcm, const snd_pcm_channel_area_t *areas, snd_pcm_uframes_t offset, snd_pcm_uframes_t size, const snd_pcm_channel_area_t *slave_areas, snd_pcm_uframes_t slave_offset, snd_pcm_uframes_t *slave_sizep) { snd_pcm_alaw_t *alaw = pcm->private_data; if (size > *slave_sizep) size = *slave_sizep; alaw->func(areas, offset, slave_areas, slave_offset, pcm->channels, size, alaw->getput_idx); *slave_sizep = size; return size; } static void snd_pcm_alaw_dump(snd_pcm_t *pcm, snd_output_t *out) { snd_pcm_alaw_t *alaw = pcm->private_data; snd_output_printf(out, "A-Law conversion PCM (%s)\n", snd_pcm_format_name(alaw->sformat)); if (pcm->setup) { snd_output_printf(out, "Its setup is:\n"); snd_pcm_dump_setup(pcm, out); } snd_output_printf(out, "Slave: "); snd_pcm_dump(alaw->plug.gen.slave, out); } static const snd_pcm_ops_t snd_pcm_alaw_ops = { .close = snd_pcm_generic_close, .info = snd_pcm_generic_info, .hw_refine = snd_pcm_alaw_hw_refine, .hw_params = snd_pcm_alaw_hw_params, .hw_free = snd_pcm_generic_hw_free, .sw_params = snd_pcm_generic_sw_params, .channel_info = snd_pcm_generic_channel_info, .dump = snd_pcm_alaw_dump, .nonblock = snd_pcm_generic_nonblock, .async = snd_pcm_generic_async, .mmap = snd_pcm_generic_mmap, .munmap = snd_pcm_generic_munmap, .query_chmaps = snd_pcm_generic_query_chmaps, .get_chmap = snd_pcm_generic_get_chmap, .set_chmap = snd_pcm_generic_set_chmap, }; /** * \brief Creates a new A-Law conversion PCM * \param pcmp Returns created PCM handle * \param name Name of PCM * \param sformat Slave (destination) format * \param slave Slave PCM handle * \param close_slave When set, the slave PCM handle is closed with copy PCM * \retval zero on success otherwise a negative error code * \warning Using of this function might be dangerous in the sense * of compatibility reasons. The prototype might be freely * changed in future. */ int snd_pcm_alaw_open(snd_pcm_t **pcmp, const char *name, snd_pcm_format_t sformat, snd_pcm_t *slave, int close_slave) { snd_pcm_t *pcm; snd_pcm_alaw_t *alaw; int err; assert(pcmp && slave); if (snd_pcm_format_linear(sformat) != 1 && sformat != SND_PCM_FORMAT_A_LAW) return -EINVAL; alaw = calloc(1, sizeof(snd_pcm_alaw_t)); if (!alaw) { return -ENOMEM; } snd_pcm_plugin_init(&alaw->plug); alaw->sformat = sformat; alaw->plug.read = snd_pcm_alaw_read_areas; alaw->plug.write = snd_pcm_alaw_write_areas; alaw->plug.undo_read = snd_pcm_plugin_undo_read_generic; alaw->plug.undo_write = snd_pcm_plugin_undo_write_generic; alaw->plug.gen.slave = slave; alaw->plug.gen.close_slave = close_slave; err = snd_pcm_new(&pcm, SND_PCM_TYPE_ALAW, name, slave->stream, slave->mode); if (err < 0) { free(alaw); return err; } pcm->ops = &snd_pcm_alaw_ops; pcm->fast_ops = &snd_pcm_plugin_fast_ops; pcm->private_data = alaw; pcm->poll_fd = slave->poll_fd; pcm->poll_events = slave->poll_events; pcm->tstamp_type = slave->tstamp_type; snd_pcm_set_hw_ptr(pcm, &alaw->plug.hw_ptr, -1, 0); snd_pcm_set_appl_ptr(pcm, &alaw->plug.appl_ptr, -1, 0); *pcmp = pcm; return 0; } /*! \page pcm_plugins \section pcm_plugins_alaw Plugin: A-Law This plugin converts A-Law samples to linear or linear to A-Law samples from master A-Law conversion PCM to given slave PCM. The channel count, format and rate must match for both of them. \code pcm.name { type alaw # A-Law conversion PCM slave STR # Slave name # or slave { # Slave definition pcm STR # Slave PCM name # or pcm { } # Slave PCM definition format STR # Slave format } } \endcode \subsection pcm_plugins_alaw_funcref Function reference */ /** * \brief Creates a new A-Law conversion PCM * \param pcmp Returns created PCM handle * \param name Name of PCM * \param root Root configuration node * \param conf Configuration node with copy PCM description * \param stream Stream type * \param mode Stream mode * \retval zero on success otherwise a negative error code * \warning Using of this function might be dangerous in the sense * of compatibility reasons. The prototype might be freely * changed in future. */ int _snd_pcm_alaw_open(snd_pcm_t **pcmp, const char *name, snd_config_t *root, snd_config_t *conf, snd_pcm_stream_t stream, int mode) { snd_config_iterator_t i, next; int err; snd_pcm_t *spcm; snd_config_t *slave = NULL, *sconf; snd_pcm_format_t sformat; snd_config_for_each(i, next, conf) { snd_config_t *n = snd_config_iterator_entry(i); const char *id; if (snd_config_get_id(n, &id) < 0) continue; if (snd_pcm_conf_generic_id(id)) continue; if (strcmp(id, "slave") == 0) { slave = n; continue; } SNDERR("Unknown field %s", id); return -EINVAL; } if (!slave) { SNDERR("slave is not defined"); return -EINVAL; } err = snd_pcm_slave_conf(root, slave, &sconf, 1, SND_PCM_HW_PARAM_FORMAT, SCONF_MANDATORY, &sformat); if (err < 0) return err; if (snd_pcm_format_linear(sformat) != 1 && sformat != SND_PCM_FORMAT_A_LAW) { snd_config_delete(sconf); SNDERR("invalid slave format"); return -EINVAL; } err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf); snd_config_delete(sconf); if (err < 0) return err; err = snd_pcm_alaw_open(pcmp, name, sformat, spcm, 1); if (err < 0) snd_pcm_close(spcm); return err; } #ifndef DOC_HIDDEN SND_DLSYM_BUILD_VERSION(_snd_pcm_alaw_open, SND_PCM_DLSYM_VERSION); #endif