| /* Copyright (c) 2012 The Chromium OS Authors. All rights reserved. |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| /* |
| * Alsa Helpers - Keeps the interface to alsa localized to this file. |
| */ |
| |
| #ifndef _CRAS_ALSA_HELPERS_H |
| #define _CRAS_ALSA_HELPERS_H |
| |
| #include <alsa/asoundlib.h> |
| #include <stdint.h> |
| #include <stdlib.h> |
| |
| struct cras_audio_format; |
| |
| /* Sets the channel layout from given format to the pcm handle. |
| * Args: |
| * handle - Pointer to the opened pcm to set channel map to. |
| * fmt - The format containing the channel layout info. |
| * Returns: |
| * 0 if a matched channel map is set to HW, -1 otherwise. |
| */ |
| int cras_alsa_set_channel_map(snd_pcm_t *handle, struct cras_audio_format *fmt); |
| |
| /* Gets the supported channel mapping of the pcm handle which matches |
| * the channel layout in the format. |
| * Args: |
| * handle - Pointer to the opened pcm to get channel map info. |
| * fmt - The format to fill channel layout into. |
| * Returns: |
| * 0 if an exactly matched channel map is found, -1 otherwise. |
| */ |
| int cras_alsa_get_channel_map(snd_pcm_t *handle, struct cras_audio_format *fmt); |
| |
| /* Opens an alsa device, thin wrapper to snd_pcm_open. |
| * Args: |
| * handle - Filled with a pointer to the opened pcm. |
| * dev - Path to the alsa device to test. |
| * stream - Alsa stream type, input or output. |
| * Returns: |
| * See docs for snd_pcm_open. |
| */ |
| int cras_alsa_pcm_open(snd_pcm_t **handle, const char *dev, |
| snd_pcm_stream_t stream); |
| |
| /* Closes an alsa device, thin wrapper to snd_pcm_close. |
| * Args: |
| * handle - Filled with a pointer to the opened pcm. |
| * Returns: |
| * See docs for snd_pcm_close. |
| */ |
| int cras_alsa_pcm_close(snd_pcm_t *handle); |
| |
| /* Starts an alsa device, thin wrapper to snd_pcm_start. |
| * Args: |
| * handle - Filled with a pointer to the opened pcm. |
| * Returns: |
| * See docs for snd_pcm_start. |
| */ |
| int cras_alsa_pcm_start(snd_pcm_t *handle); |
| |
| /* Drains an alsa device, thin wrapper to snd_pcm_drain. |
| * Args: |
| * handle - Filled with a pointer to the opened pcm. |
| * Returns: |
| * See docs for snd_pcm_drain. |
| */ |
| int cras_alsa_pcm_drain(snd_pcm_t *handle); |
| |
| /* Forward/rewind appl_ptr so it becomes ahead of hw_ptr by fuzz samples. |
| * After moving appl_ptr, device can play the new samples as quick as possible. |
| * avail = buffer_frames - appl_ptr + hw_ptr |
| * => hw_ptr - appl_ptr = avail - buffer_frames. |
| * The difference between hw_ptr and app_ptr can be inferred from snd_pcm_avail. |
| * So the amount of frames to forward appl_ptr is |
| * avail - buffer_frames + fuzz. |
| * When hw_ptr is wrapped around boundary, this value may be negative. Use |
| * snd_pcm_rewind to move appl_ptr backward. |
| * |
| * Case 1: avail - buffer_frames + fuzz > 0 |
| * |
| * -------|----------|----------------------------------- |
| * app_ptr hw_ptr |
| * |------------->| forward target |
| * |
| * Case 2: avail - buffer_frames + fuzz < 0 |
| * |
| * -------|----------|----------------------------------- |
| * hw_ptr app_ptr |
| * |<------| rewind target |
| * |
| * Args: |
| * handle - Filled with a pointer to the opened pcm. |
| * ahead - Number of frames appl_ptr should be ahead of hw_ptr. |
| * Returns: |
| * 0 on success. A negative error code on failure. |
| */ |
| int cras_alsa_resume_appl_ptr(snd_pcm_t *handle, snd_pcm_uframes_t ahead); |
| |
| /* Probes properties of the alsa device. |
| * Args: |
| * handle - The open PCM to configure. |
| * rates - Pointer that will be set to the arrary of valid samples rates. |
| * Must be freed by the caller. |
| * channel_counts - Pointer that will be set to the array of valid channel |
| * counts. Must be freed by the caller. |
| * formats - Pointer that will be set to the arrary of valid PCM formats. |
| * Must be freed by the caller. |
| * Returns: |
| * 0 on success. On failure an error code from alsa or -ENOMEM. |
| */ |
| int cras_alsa_fill_properties(snd_pcm_t *handle, size_t **rates, |
| size_t **channel_counts, |
| snd_pcm_format_t **formats); |
| |
| /* Sets up the hwparams to alsa. |
| * Args: |
| * handle - The open PCM to configure. |
| * format - The audio format desired for playback/capture. |
| * buffer_frames - Number of frames in the ALSA buffer. |
| * period_wakeup - Flag to determine if period_wakeup is required |
| * 0 - disable, 1 - enable |
| * dma_period_time - If non-zero, set the dma period time to this value |
| * (in microseconds). |
| * Returns: |
| * 0 on success, negative error on failure. |
| */ |
| int cras_alsa_set_hwparams(snd_pcm_t *handle, struct cras_audio_format *format, |
| snd_pcm_uframes_t *buffer_frames, int period_wakeup, |
| unsigned int dma_period_time); |
| |
| /* Sets up the swparams to alsa. |
| * Args: |
| * handle - The open PCM to configure. |
| * Returns: |
| * 0 on success, negative error on failure. |
| */ |
| int cras_alsa_set_swparams(snd_pcm_t *handle); |
| |
| /* Get the number of used frames in the alsa buffer. |
| * |
| * When underrun is not severe, this function masks the underrun situation |
| * and set avail as 0. When underrun is severe, returns -EPIPE so caller |
| * can handle it. |
| * Args: |
| * handle[in] - The open PCM to configure. |
| * buf_size[in] - Number of frames in the ALSA buffer. |
| * severe_underrun_frames[in] - Number of frames as the threshold for severe |
| * underrun. |
| * dev_name[in] - Device name for logging. |
| * avail[out] - Filled with the number of frames available in the buffer. |
| * tstamp[out] - Filled with the hardware timestamp for the available frames. |
| * This value is {0, 0} when the device hasn't actually started |
| * reading or writing frames. |
| * Returns: |
| * 0 on success, negative error on failure. -EPIPE if severe underrun |
| * happens. |
| */ |
| int cras_alsa_get_avail_frames(snd_pcm_t *handle, snd_pcm_uframes_t buf_size, |
| snd_pcm_uframes_t severe_underrun_frames, |
| const char *dev_name, snd_pcm_uframes_t *avail, |
| struct timespec *tstamp); |
| |
| /* Get the current alsa delay, make sure it's no bigger than the buffer size. |
| * Args: |
| * handle - The open PCM to configure. |
| * buf_size - Number of frames in the ALSA buffer. |
| * delay - Filled with the number of delay frames. |
| * Returns: |
| * 0 on success, negative error on failure. |
| */ |
| int cras_alsa_get_delay_frames(snd_pcm_t *handle, snd_pcm_uframes_t buf_size, |
| snd_pcm_sframes_t *delay); |
| |
| /* Wrapper for snd_pcm_mmap_begin where only buffer is concerned. |
| * Offset and frames from cras_alsa_mmap_begin are neglected. |
| * Args: |
| * handle - The open PCM to configure. |
| * dst - Pointer set to the area for reading/writing the audio. |
| * Returns: |
| * zero on success, negative error code for fatal errors. |
| */ |
| int cras_alsa_mmap_get_whole_buffer(snd_pcm_t *handle, uint8_t **dst); |
| |
| /* Wrapper for snd_pcm_mmap_begin |
| * Args: |
| * handle - The open PCM to configure. |
| * format_bytes - Number of bytes in a single frame. |
| * dst - Pointer set to the area for reading/writing the audio. |
| * offset - Filled with the offset to pass back to commit. |
| * frames - Passed with the max number of frames to request. Filled with the |
| * max number to use. |
| * Returns: |
| * zero on success, negative error code for fatal |
| * errors. |
| */ |
| int cras_alsa_mmap_begin(snd_pcm_t *handle, unsigned int format_bytes, |
| uint8_t **dst, snd_pcm_uframes_t *offset, |
| snd_pcm_uframes_t *frames); |
| |
| /* Wrapper for snd_pcm_mmap_commit |
| * Args: |
| * handle - The open PCM to configure. |
| * offset - offset from call to mmap_begin. |
| * frames - # of frames written/read. |
| * Returns: |
| * zero on success, negative error code for fatal |
| * errors. |
| */ |
| int cras_alsa_mmap_commit(snd_pcm_t *handle, snd_pcm_uframes_t offset, |
| snd_pcm_uframes_t frames); |
| |
| /* When the stream is suspended, due to a system suspend, loop until we can |
| * resume it. Won't actually loop very much because the system will be |
| * suspended. |
| * Args: |
| * handle - The open PCM to configure. |
| * Returns: |
| * zero on success, negative error code for fatal |
| * errors. |
| */ |
| int cras_alsa_attempt_resume(snd_pcm_t *handle); |
| |
| #endif /* _CRAS_ALSA_HELPERS_H */ |
