1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * Helper functions for indirect PCM data transfer 4 * 5 * Copyright (c) by Takashi Iwai <tiwai@suse.de> 6 * Jaroslav Kysela <perex@perex.cz> 7 */ 8 9 #ifndef __SOUND_PCM_INDIRECT_H 10 #define __SOUND_PCM_INDIRECT_H 11 12 #include <sound/pcm.h> 13 14 struct snd_pcm_indirect { 15 unsigned int hw_buffer_size; /* Byte size of hardware buffer */ 16 unsigned int hw_queue_size; /* Max queue size of hw buffer (0 = buffer size) */ 17 unsigned int hw_data; /* Offset to next dst (or src) in hw ring buffer */ 18 unsigned int hw_io; /* Ring buffer hw pointer */ 19 int hw_ready; /* Bytes ready for play (or captured) in hw ring buffer */ 20 unsigned int sw_buffer_size; /* Byte size of software buffer */ 21 unsigned int sw_data; /* Offset to next dst (or src) in sw ring buffer */ 22 unsigned int sw_io; /* Current software pointer in bytes */ 23 int sw_ready; /* Bytes ready to be transferred to/from hw */ 24 snd_pcm_uframes_t appl_ptr; /* Last seen appl_ptr */ 25 }; 26 27 typedef void (*snd_pcm_indirect_copy_t)(struct snd_pcm_substream *substream, 28 struct snd_pcm_indirect *rec, size_t bytes); 29 30 /* 31 * helper function for playback ack callback 32 */ 33 static inline int 34 snd_pcm_indirect_playback_transfer(struct snd_pcm_substream *substream, 35 struct snd_pcm_indirect *rec, 36 snd_pcm_indirect_copy_t copy) 37 { 38 struct snd_pcm_runtime *runtime = substream->runtime; 39 snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr; 40 snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr; 41 int qsize; 42 43 if (diff) { 44 if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2)) 45 diff += runtime->boundary; 46 if (diff < 0) 47 return -EPIPE; 48 rec->sw_ready += (int)frames_to_bytes(runtime, diff); 49 rec->appl_ptr = appl_ptr; 50 } 51 qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size; 52 while (rec->hw_ready < qsize && rec->sw_ready > 0) { 53 unsigned int hw_to_end = rec->hw_buffer_size - rec->hw_data; 54 unsigned int sw_to_end = rec->sw_buffer_size - rec->sw_data; 55 unsigned int bytes = qsize - rec->hw_ready; 56 if (rec->sw_ready < (int)bytes) 57 bytes = rec->sw_ready; 58 if (hw_to_end < bytes) 59 bytes = hw_to_end; 60 if (sw_to_end < bytes) 61 bytes = sw_to_end; 62 if (! bytes) 63 break; 64 copy(substream, rec, bytes); 65 rec->hw_data += bytes; 66 if (rec->hw_data == rec->hw_buffer_size) 67 rec->hw_data = 0; 68 rec->sw_data += bytes; 69 if (rec->sw_data == rec->sw_buffer_size) 70 rec->sw_data = 0; 71 rec->hw_ready += bytes; 72 rec->sw_ready -= bytes; 73 } 74 return 0; 75 } 76 77 /* 78 * helper function for playback pointer callback 79 * ptr = current byte pointer 80 */ 81 static inline snd_pcm_uframes_t 82 snd_pcm_indirect_playback_pointer(struct snd_pcm_substream *substream, 83 struct snd_pcm_indirect *rec, unsigned int ptr) 84 { 85 int bytes = ptr - rec->hw_io; 86 int err; 87 88 if (bytes < 0) 89 bytes += rec->hw_buffer_size; 90 rec->hw_io = ptr; 91 rec->hw_ready -= bytes; 92 rec->sw_io += bytes; 93 if (rec->sw_io >= rec->sw_buffer_size) 94 rec->sw_io -= rec->sw_buffer_size; 95 if (substream->ops->ack) { 96 err = substream->ops->ack(substream); 97 if (err == -EPIPE) 98 return SNDRV_PCM_POS_XRUN; 99 } 100 return bytes_to_frames(substream->runtime, rec->sw_io); 101 } 102 103 104 /* 105 * helper function for capture ack callback 106 */ 107 static inline int 108 snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream, 109 struct snd_pcm_indirect *rec, 110 snd_pcm_indirect_copy_t copy) 111 { 112 struct snd_pcm_runtime *runtime = substream->runtime; 113 snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr; 114 snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr; 115 116 if (diff) { 117 if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2)) 118 diff += runtime->boundary; 119 if (diff < 0) 120 return -EPIPE; 121 rec->sw_ready -= frames_to_bytes(runtime, diff); 122 rec->appl_ptr = appl_ptr; 123 } 124 while (rec->hw_ready > 0 && 125 rec->sw_ready < (int)rec->sw_buffer_size) { 126 size_t hw_to_end = rec->hw_buffer_size - rec->hw_data; 127 size_t sw_to_end = rec->sw_buffer_size - rec->sw_data; 128 size_t bytes = rec->sw_buffer_size - rec->sw_ready; 129 if (rec->hw_ready < (int)bytes) 130 bytes = rec->hw_ready; 131 if (hw_to_end < bytes) 132 bytes = hw_to_end; 133 if (sw_to_end < bytes) 134 bytes = sw_to_end; 135 if (! bytes) 136 break; 137 copy(substream, rec, bytes); 138 rec->hw_data += bytes; 139 if ((int)rec->hw_data == rec->hw_buffer_size) 140 rec->hw_data = 0; 141 rec->sw_data += bytes; 142 if (rec->sw_data == rec->sw_buffer_size) 143 rec->sw_data = 0; 144 rec->hw_ready -= bytes; 145 rec->sw_ready += bytes; 146 } 147 return 0; 148 } 149 150 /* 151 * helper function for capture pointer callback, 152 * ptr = current byte pointer 153 */ 154 static inline snd_pcm_uframes_t 155 snd_pcm_indirect_capture_pointer(struct snd_pcm_substream *substream, 156 struct snd_pcm_indirect *rec, unsigned int ptr) 157 { 158 int qsize; 159 int bytes = ptr - rec->hw_io; 160 int err; 161 162 if (bytes < 0) 163 bytes += rec->hw_buffer_size; 164 rec->hw_io = ptr; 165 rec->hw_ready += bytes; 166 qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size; 167 if (rec->hw_ready > qsize) 168 return SNDRV_PCM_POS_XRUN; 169 rec->sw_io += bytes; 170 if (rec->sw_io >= rec->sw_buffer_size) 171 rec->sw_io -= rec->sw_buffer_size; 172 if (substream->ops->ack) { 173 err = substream->ops->ack(substream); 174 if (err == -EPIPE) 175 return SNDRV_PCM_POS_XRUN; 176 } 177 return bytes_to_frames(substream->runtime, rec->sw_io); 178 } 179 180 #endif /* __SOUND_PCM_INDIRECT_H */ 181