[5/7] audio: Let HWVoice write() handlers take a const buffer

diff --git a/audio/audio_int.h b/audio/audio_int.h
index 62829de4e8..d23722ae7c 100644
--- a/audio/audio_int.h
+++ b/audio/audio_int.h
@@ -152,7 +152,7 @@  struct audio_driver {
 struct audio_pcm_ops {
     int    (*init_out)(HWVoiceOut *hw, audsettings *as, void *drv_opaque);
     void   (*fini_out)(HWVoiceOut *hw);
-    size_t (*write)   (HWVoiceOut *hw, void *buf, size_t size);
+    size_t (*write)   (HWVoiceOut *hw, const void *buf, size_t size);
     void   (*run_buffer_out)(HWVoiceOut *hw);
     /*
      * get a buffer that after later can be passed to put_buffer_out; optional
@@ -165,7 +165,7 @@  struct audio_pcm_ops {
      * buf must be equal the pointer returned by get_buffer_out,
      * size may be smaller
      */
-    size_t (*put_buffer_out)(HWVoiceOut *hw, void *buf, size_t size);
+    size_t (*put_buffer_out)(HWVoiceOut *hw, const void *buf, size_t size);
     void   (*enable_out)(HWVoiceOut *hw, bool enable);
     void   (*volume_out)(HWVoiceOut *hw, Volume *vol);
 
@@ -173,17 +173,18 @@  struct audio_pcm_ops {
     void   (*fini_in) (HWVoiceIn *hw);
     size_t (*read)    (HWVoiceIn *hw, void *buf, size_t size);
     void  *(*get_buffer_in)(HWVoiceIn *hw, size_t *size);
-    void   (*put_buffer_in)(HWVoiceIn *hw, void *buf, size_t size);
+    void   (*put_buffer_in)(HWVoiceIn *hw, const void *buf, size_t size);
     void   (*enable_in)(HWVoiceIn *hw, bool enable);
     void   (*volume_in)(HWVoiceIn *hw, Volume *vol);
 };
 
 void *audio_generic_get_buffer_in(HWVoiceIn *hw, size_t *size);
-void audio_generic_put_buffer_in(HWVoiceIn *hw, void *buf, size_t size);
+void audio_generic_put_buffer_in(HWVoiceIn *hw, const void *buf, size_t size);
 void audio_generic_run_buffer_out(HWVoiceOut *hw);
 void *audio_generic_get_buffer_out(HWVoiceOut *hw, size_t *size);
-size_t audio_generic_put_buffer_out(HWVoiceOut *hw, void *buf, size_t size);
-size_t audio_generic_write(HWVoiceOut *hw, void *buf, size_t size);
+size_t audio_generic_put_buffer_out(HWVoiceOut *hw,
+                                    const void *buf, size_t size);
+size_t audio_generic_write(HWVoiceOut *hw, const void *buf, size_t size);
 size_t audio_generic_read(HWVoiceIn *hw, void *buf, size_t size);
 
 struct capture_callback {
diff --git a/audio/alsaaudio.c b/audio/alsaaudio.c
index a32db8ff39..7692ee5524 100644
--- a/audio/alsaaudio.c
+++ b/audio/alsaaudio.c
@@ -608,7 +608,7 @@  static int alsa_open(bool in, struct alsa_params_req *req,
     return -1;
 }
 
-static size_t alsa_write(HWVoiceOut *hw, void *buf, size_t len)
+static size_t alsa_write(HWVoiceOut *hw, const void *buf, size_t len)
 {
     ALSAVoiceOut *alsa = (ALSAVoiceOut *) hw;
     size_t pos = 0;
diff --git a/audio/audio.c b/audio/audio.c
index c75455bbb5..e2932da4f0 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -1253,7 +1253,7 @@  static size_t audio_pcm_hw_run_in(HWVoiceIn *hw, size_t samples)
     while (samples) {
         size_t proc;
         size_t size = samples * hw->info.bytes_per_frame;
-        void *buf = hw->pcm_ops->get_buffer_in(hw, &size);
+        const void *buf = hw->pcm_ops->get_buffer_in(hw, &size);
 
         assert(size % hw->info.bytes_per_frame == 0);
         if (size == 0) {
@@ -1425,7 +1425,7 @@  void *audio_generic_get_buffer_in(HWVoiceIn *hw, size_t *size)
     return hw->buf_emul + start;
 }
 
-void audio_generic_put_buffer_in(HWVoiceIn *hw, void *buf, size_t size)
+void audio_generic_put_buffer_in(HWVoiceIn *hw, const void *buf, size_t size)
 {
     assert(size <= hw->pending_emul);
     hw->pending_emul -= size;
@@ -1468,7 +1468,8 @@  void *audio_generic_get_buffer_out(HWVoiceOut *hw, size_t *size)
     return hw->buf_emul + hw->pos_emul;
 }
 
-size_t audio_generic_put_buffer_out(HWVoiceOut *hw, void *buf, size_t size)
+size_t audio_generic_put_buffer_out(HWVoiceOut *hw,
+                                    const void *buf, size_t size)
 {
     assert(buf == hw->buf_emul + hw->pos_emul &&
            size + hw->pending_emul <= hw->size_emul);
@@ -1479,7 +1480,7 @@  size_t audio_generic_put_buffer_out(HWVoiceOut *hw, void *buf, size_t size)
     return size;
 }
 
-size_t audio_generic_write(HWVoiceOut *hw, void *buf, size_t size)
+size_t audio_generic_write(HWVoiceOut *hw, const void *buf, size_t size)
 {
     size_t dst_size, copy_size;
     void *dst = hw->pcm_ops->get_buffer_out(hw, &dst_size);
@@ -1491,7 +1492,7 @@  size_t audio_generic_write(HWVoiceOut *hw, void *buf, size_t size)
 
 size_t audio_generic_read(HWVoiceIn *hw, void *buf, size_t size)
 {
-    void *src = hw->pcm_ops->get_buffer_in(hw, &size);
+    const void *src = hw->pcm_ops->get_buffer_in(hw, &size);
 
     memcpy(buf, src, size);
     hw->pcm_ops->put_buffer_in(hw, src, size);
diff --git a/audio/coreaudio.c b/audio/coreaudio.c
index 4b4365660f..5258871c9c 100644
--- a/audio/coreaudio.c
+++ b/audio/coreaudio.c
@@ -412,9 +412,10 @@  static int coreaudio_unlock (coreaudioVoiceOut *core, const char *fn_name)
 COREAUDIO_WRAPPER_FUNC(get_buffer_out, void *, (HWVoiceOut *hw, size_t *size),
                        (hw, size))
 COREAUDIO_WRAPPER_FUNC(put_buffer_out, size_t,
-                       (HWVoiceOut *hw, void *buf, size_t size),
+                       (HWVoiceOut *hw, const void *buf, size_t size),
                        (hw, buf, size))
-COREAUDIO_WRAPPER_FUNC(write, size_t, (HWVoiceOut *hw, void *buf, size_t size),
+COREAUDIO_WRAPPER_FUNC(write, size_t,
+                       (HWVoiceOut *hw, const void *buf, size_t size),
                        (hw, buf, size))
 #undef COREAUDIO_WRAPPER_FUNC
 
diff --git a/audio/dsoundaudio.c b/audio/dsoundaudio.c
index 4cdf19ab67..bba6bafda4 100644
--- a/audio/dsoundaudio.c
+++ b/audio/dsoundaudio.c
@@ -454,7 +454,7 @@  static void *dsound_get_buffer_out(HWVoiceOut *hw, size_t *size)
     return ret;
 }
 
-static size_t dsound_put_buffer_out(HWVoiceOut *hw, void *buf, size_t len)
+static size_t dsound_put_buffer_out(HWVoiceOut *hw, const void *buf, size_t len)
 {
     DSoundVoiceOut *ds = (DSoundVoiceOut *) hw;
     LPDIRECTSOUNDBUFFER dsb = ds->dsound_buffer;
diff --git a/audio/noaudio.c b/audio/noaudio.c
index 05798ea210..21995c7d9b 100644
--- a/audio/noaudio.c
+++ b/audio/noaudio.c
@@ -41,7 +41,7 @@  typedef struct NoVoiceIn {
     RateCtl rate;
 } NoVoiceIn;
 
-static size_t no_write(HWVoiceOut *hw, void *buf, size_t len)
+static size_t no_write(HWVoiceOut *hw, const void *buf, size_t len)
 {
     NoVoiceOut *no = (NoVoiceOut *) hw;
     return audio_rate_get_bytes(&hw->info, &no->rate, len);
diff --git a/audio/ossaudio.c b/audio/ossaudio.c
index 7778138df5..97bde0256e 100644
--- a/audio/ossaudio.c
+++ b/audio/ossaudio.c
@@ -402,7 +402,7 @@  static void *oss_get_buffer_out(HWVoiceOut *hw, size_t *size)
     }
 }
 
-static size_t oss_put_buffer_out(HWVoiceOut *hw, void *buf, size_t size)
+static size_t oss_put_buffer_out(HWVoiceOut *hw, const void *buf, size_t size)
 {
     OSSVoiceOut *oss = (OSSVoiceOut *) hw;
     if (oss->mmapped) {
@@ -415,7 +415,7 @@  static size_t oss_put_buffer_out(HWVoiceOut *hw, void *buf, size_t size)
     }
 }
 
-static size_t oss_write(HWVoiceOut *hw, void *buf, size_t len)
+static size_t oss_write(HWVoiceOut *hw, const void *buf, size_t len)
 {
     OSSVoiceOut *oss = (OSSVoiceOut *) hw;
     size_t pos;
diff --git a/audio/paaudio.c b/audio/paaudio.c
index b052084698..b50df15ea7 100644
--- a/audio/paaudio.c
+++ b/audio/paaudio.c
@@ -125,7 +125,7 @@  unlock_and_fail:
     return NULL;
 }
 
-static void qpa_put_buffer_in(HWVoiceIn *hw, void *buf, size_t size)
+static void qpa_put_buffer_in(HWVoiceIn *hw, const void *buf, size_t size)
 {
     PAVoiceIn *p = (PAVoiceIn *) hw;
     PAConnection *c = p->g->conn;
@@ -228,7 +228,7 @@  unlock_and_fail:
     return NULL;
 }
 
-static size_t qpa_write(HWVoiceOut *hw, void *data, size_t length)
+static size_t qpa_write(HWVoiceOut *hw, const void *data, size_t length)
 {
     PAVoiceOut *p = (PAVoiceOut *) hw;
     PAConnection *c = p->g->conn;
diff --git a/audio/sdlaudio.c b/audio/sdlaudio.c
index 21b7a0484b..9d740186cc 100644
--- a/audio/sdlaudio.c
+++ b/audio/sdlaudio.c
@@ -256,10 +256,12 @@  static void sdl_callback (void *opaque, Uint8 *buf, int len)
 SDL_WRAPPER_FUNC(get_buffer_out, void *, (HWVoiceOut *hw, size_t *size),
                  (hw, size), *size = 0, sdl_unlock)
 SDL_WRAPPER_FUNC(put_buffer_out, size_t,
-                 (HWVoiceOut *hw, void *buf, size_t size), (hw, buf, size),
+                 (HWVoiceOut *hw, const void *buf, size_t size),
+                 (hw, buf, size),
                  /*nothing*/, sdl_unlock_and_post)
 SDL_WRAPPER_FUNC(write, size_t,
-                 (HWVoiceOut *hw, void *buf, size_t size), (hw, buf, size),
+                 (HWVoiceOut *hw, const void *buf, size_t size),
+                 (hw, buf, size),
                  /*nothing*/, sdl_unlock_and_post)
 
 #undef SDL_WRAPPER_FUNC
diff --git a/audio/spiceaudio.c b/audio/spiceaudio.c
index b6b5da4812..0aa6a0a671 100644
--- a/audio/spiceaudio.c
+++ b/audio/spiceaudio.c
@@ -139,7 +139,7 @@  static void *line_out_get_buffer(HWVoiceOut *hw, size_t *size)
     return out->frame + out->fpos;
 }
 
-static size_t line_out_put_buffer(HWVoiceOut *hw, void *buf, size_t size)
+static size_t line_out_put_buffer(HWVoiceOut *hw, const void *buf, size_t size)
 {
     SpiceVoiceOut *out = container_of(hw, SpiceVoiceOut, hw);
 
diff --git a/audio/wavaudio.c b/audio/wavaudio.c
index 20e6853f85..64d7142a97 100644
--- a/audio/wavaudio.c
+++ b/audio/wavaudio.c
@@ -39,7 +39,7 @@  typedef struct WAVVoiceOut {
     int total_samples;
 } WAVVoiceOut;
 
-static size_t wav_write_out(HWVoiceOut *hw, void *buf, size_t len)
+static size_t wav_write_out(HWVoiceOut *hw, const void *buf, size_t len)
 {
     WAVVoiceOut *wav = (WAVVoiceOut *) hw;
     int64_t bytes = audio_rate_get_bytes(&hw->info, &wav->rate, len);