[v3,01/15] audio: replace open-coded buffer arithmetic

Replace open-coded buffer arithmetic with the new function
audio_ring_posb(). That's the position in backward direction
of a given point at a given distance.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
---
 audio/audio.c     | 25 +++++++------------------
 audio/audio_int.h | 13 +++++++++++++
 audio/coreaudio.c | 10 ++++------
 audio/sdlaudio.c  | 11 +++++------
 4 files changed, 29 insertions(+), 30 deletions(-)

Reviewed-by: Akihiko Odaki <akihiko.odaki@gmail.com>

On 2022/03/02 4:12, Volker Rümelin wrote:
> Replace open-coded buffer arithmetic with the new function
> audio_ring_posb(). That's the position in backward direction
> of a given point at a given distance.
> 
> Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
> ---
>   audio/audio.c     | 25 +++++++------------------
>   audio/audio_int.h | 13 +++++++++++++
>   audio/coreaudio.c | 10 ++++------
>   audio/sdlaudio.c  | 11 +++++------
>   4 files changed, 29 insertions(+), 30 deletions(-)
> 
> diff --git a/audio/audio.c b/audio/audio.c
> index dc28685d22..e7a139e289 100644
> --- a/audio/audio.c
> +++ b/audio/audio.c
> @@ -574,19 +574,13 @@ static size_t audio_pcm_sw_get_rpos_in(SWVoiceIn *sw)
>   {
>       HWVoiceIn *hw = sw->hw;
>       ssize_t live = hw->total_samples_captured - sw->total_hw_samples_acquired;
> -    ssize_t rpos;
>   
>       if (audio_bug(__func__, live < 0 || live > hw->conv_buf->size)) {
>           dolog("live=%zu hw->conv_buf->size=%zu\n", live, hw->conv_buf->size);
>           return 0;
>       }
>   
> -    rpos = hw->conv_buf->pos - live;
> -    if (rpos >= 0) {
> -        return rpos;
> -    } else {
> -        return hw->conv_buf->size + rpos;
> -    }
> +    return audio_ring_posb(hw->conv_buf->pos, live, hw->conv_buf->size);
>   }
>   
>   static size_t audio_pcm_sw_read(SWVoiceIn *sw, void *buf, size_t size)
> @@ -1394,12 +1388,10 @@ void audio_generic_run_buffer_in(HWVoiceIn *hw)
>   
>   void *audio_generic_get_buffer_in(HWVoiceIn *hw, size_t *size)
>   {
> -    ssize_t start = (ssize_t)hw->pos_emul - hw->pending_emul;
> +    size_t start;
>   
> -    if (start < 0) {
> -        start += hw->size_emul;
> -    }
> -    assert(start >= 0 && start < hw->size_emul);
> +    start = audio_ring_posb(hw->pos_emul, hw->pending_emul, hw->size_emul);
> +    assert(start < hw->size_emul);
>   
>       *size = MIN(*size, hw->pending_emul);
>       *size = MIN(*size, hw->size_emul - start);
> @@ -1415,13 +1407,10 @@ void audio_generic_put_buffer_in(HWVoiceIn *hw, void *buf, size_t size)
>   void audio_generic_run_buffer_out(HWVoiceOut *hw)
>   {
>       while (hw->pending_emul) {
> -        size_t write_len, written;
> -        ssize_t start = ((ssize_t) hw->pos_emul) - hw->pending_emul;
> +        size_t write_len, written, start;
>   
> -        if (start < 0) {
> -            start += hw->size_emul;
> -        }
> -        assert(start >= 0 && start < hw->size_emul);
> +        start = audio_ring_posb(hw->pos_emul, hw->pending_emul, hw->size_emul);
> +        assert(start < hw->size_emul);
>   
>           write_len = MIN(hw->pending_emul, hw->size_emul - start);
>   
> diff --git a/audio/audio_int.h b/audio/audio_int.h
> index 428a091d05..71be162271 100644
> --- a/audio/audio_int.h
> +++ b/audio/audio_int.h
> @@ -266,6 +266,19 @@ static inline size_t audio_ring_dist(size_t dst, size_t src, size_t len)
>       return (dst >= src) ? (dst - src) : (len - src + dst);
>   }
>   
> +/**
> + * audio_ring_posb() - returns new position in ringbuffer in backward
> + * direction at given distance
> + *
> + * @pos: current position in ringbuffer
> + * @dist: distance in ringbuffer to walk in reverse direction
> + * @len: size of ringbuffer
> + */
> +static inline size_t audio_ring_posb(size_t pos, size_t dist, size_t len)
> +{
> +    return pos >= dist ? pos - dist : len - dist + pos;
> +}
> +
>   #define dolog(fmt, ...) AUD_log(AUDIO_CAP, fmt, ## __VA_ARGS__)
>   
>   #ifdef DEBUG
> diff --git a/audio/coreaudio.c b/audio/coreaudio.c
> index d8a21d3e50..1fdd1d4b14 100644
> --- a/audio/coreaudio.c
> +++ b/audio/coreaudio.c
> @@ -333,12 +333,10 @@ static OSStatus audioDeviceIOProc(
>   
>       len = frameCount * hw->info.bytes_per_frame;
>       while (len) {
> -        size_t write_len;
> -        ssize_t start = ((ssize_t) hw->pos_emul) - hw->pending_emul;
> -        if (start < 0) {
> -            start += hw->size_emul;
> -        }
> -        assert(start >= 0 && start < hw->size_emul);
> +        size_t write_len, start;
> +
> +        start = audio_ring_posb(hw->pos_emul, hw->pending_emul, hw->size_emul);
> +        assert(start < hw->size_emul);
>   
>           write_len = MIN(MIN(hw->pending_emul, len),
>                           hw->size_emul - start);
> diff --git a/audio/sdlaudio.c b/audio/sdlaudio.c
> index c68c62a3e4..d6f3aa1a9a 100644
> --- a/audio/sdlaudio.c
> +++ b/audio/sdlaudio.c
> @@ -224,12 +224,11 @@ static void sdl_callback_out(void *opaque, Uint8 *buf, int len)
>           /* dolog("callback_out: len=%d avail=%zu\n", len, hw->pending_emul); */
>   
>           while (hw->pending_emul && len) {
> -            size_t write_len;
> -            ssize_t start = (ssize_t)hw->pos_emul - hw->pending_emul;
> -            if (start < 0) {
> -                start += hw->size_emul;
> -            }
> -            assert(start >= 0 && start < hw->size_emul);
> +            size_t write_len, start;
> +
> +            start = audio_ring_posb(hw->pos_emul, hw->pending_emul,
> +                                    hw->size_emul);
> +            assert(start < hw->size_emul);
>   
>               write_len = MIN(MIN(hw->pending_emul, len),
>                               hw->size_emul - start)