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 -EINVAL; 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 if (bytes < 0) 87 bytes += rec->hw_buffer_size; 88 rec->hw_io = ptr; 89 rec->hw_ready -= bytes; 90 rec->sw_io += bytes; 91 if (rec->sw_io >= rec->sw_buffer_size) 92 rec->sw_io -= rec->sw_buffer_size; 93 if (substream->ops->ack) 94 substream->ops->ack(substream); 95 return bytes_to_frames(substream->runtime, rec->sw_io); 96 } 97 98 99 /* 100 * helper function for capture ack callback 101 */ 102 static inline int 103 snd_pcm_indirect_capture_transfer(struct snd_pcm_substream *substream, 104 struct snd_pcm_indirect *rec, 105 snd_pcm_indirect_copy_t copy) 106 { 107 struct snd_pcm_runtime *runtime = substream->runtime; 108 snd_pcm_uframes_t appl_ptr = runtime->control->appl_ptr; 109 snd_pcm_sframes_t diff = appl_ptr - rec->appl_ptr; 110 111 if (diff) { 112 if (diff < -(snd_pcm_sframes_t) (runtime->boundary / 2)) 113 diff += runtime->boundary; 114 if (diff < 0) 115 return -EINVAL; 116 rec->sw_ready -= frames_to_bytes(runtime, diff); 117 rec->appl_ptr = appl_ptr; 118 } 119 while (rec->hw_ready > 0 && 120 rec->sw_ready < (int)rec->sw_buffer_size) { 121 size_t hw_to_end = rec->hw_buffer_size - rec->hw_data; 122 size_t sw_to_end = rec->sw_buffer_size - rec->sw_data; 123 size_t bytes = rec->sw_buffer_size - rec->sw_ready; 124 if (rec->hw_ready < (int)bytes) 125 bytes = rec->hw_ready; 126 if (hw_to_end < bytes) 127 bytes = hw_to_end; 128 if (sw_to_end < bytes) 129 bytes = sw_to_end; 130 if (! bytes) 131 break; 132 copy(substream, rec, bytes); 133 rec->hw_data += bytes; 134 if ((int)rec->hw_data == rec->hw_buffer_size) 135 rec->hw_data = 0; 136 rec->sw_data += bytes; 137 if (rec->sw_data == rec->sw_buffer_size) 138 rec->sw_data = 0; 139 rec->hw_ready -= bytes; 140 rec->sw_ready += bytes; 141 } 142 return 0; 143 } 144 145 /* 146 * helper function for capture pointer callback, 147 * ptr = current byte pointer 148 */ 149 static inline snd_pcm_uframes_t 150 snd_pcm_indirect_capture_pointer(struct snd_pcm_substream *substream, 151 struct snd_pcm_indirect *rec, unsigned int ptr) 152 { 153 int qsize; 154 int bytes = ptr - rec->hw_io; 155 if (bytes < 0) 156 bytes += rec->hw_buffer_size; 157 rec->hw_io = ptr; 158 rec->hw_ready += bytes; 159 qsize = rec->hw_queue_size ? rec->hw_queue_size : rec->hw_buffer_size; 160 if (rec->hw_ready > qsize) 161 return SNDRV_PCM_POS_XRUN; 162 rec->sw_io += bytes; 163 if (rec->sw_io >= rec->sw_buffer_size) 164 rec->sw_io -= rec->sw_buffer_size; 165 if (substream->ops->ack) 166 substream->ops->ack(substream); 167 return bytes_to_frames(substream->runtime, rec->sw_io); 168 } 169 170 #endif /* __SOUND_PCM_INDIRECT_H */ 171