Simplify channel handling in the sndio backend

1 files changed, 63 insertions, 89 deletions

diff --git a/alc/backends/sndio.cpp b/alc/backends/sndio.cpp
index 2d8b424c..c41c6c8b 100644
--- a/alc/backends/sndio.cpp
+++ b/alc/backends/sndio.cpp
@@ -44,6 +44,11 @@ namespace {
 
 static const char sndio_device[] = "SndIO Default";
 
+struct SioPar : public sio_par {
+    SioPar() { sio_initpar(this); }
+
+    void clear() { sio_initpar(this); }
+};
 
 struct SndioPlayback final : public BackendBase {
     SndioPlayback(DeviceBase *device) noexcept : BackendBase{device} { }
@@ -57,6 +62,7 @@ struct SndioPlayback final : public BackendBase {
     void stop() override;
 
     sio_hdl *mSndHandle{nullptr};
+    uint mFrameStep{};
 
     al::vector<al::byte> mBuffer;
 
@@ -75,16 +81,8 @@ SndioPlayback::~SndioPlayback()
 
 int SndioPlayback::mixerProc()
 {
-    sio_par par;
-    sio_initpar(&par);
-    if(!sio_getpar(mSndHandle, &par))
-    {
-        mDevice->handleDisconnect("Failed to get device parameters");
-        return 1;
-    }
-
-    const size_t frameStep{par.pchan};
-    const size_t frameSize{frameStep * par.bps};
+    const size_t frameStep{mFrameStep};
+    const size_t frameSize{frameStep * mDevice->bytesFromFmt()};
 
     SetRTPriority();
     althrd_setname(MIXER_THREAD_NAME);
@@ -92,22 +90,20 @@ int SndioPlayback::mixerProc()
     while(!mKillNow.load(std::memory_order_acquire)
         && mDevice->Connected.load(std::memory_order_acquire))
     {
-        al::byte *WritePtr{mBuffer.data()};
-        size_t len{mBuffer.size()};
+        al::span<al::byte> buffer{mBuffer};
 
-        mDevice->renderSamples(WritePtr, static_cast<uint>(len/frameSize), frameStep);
-        while(len > 0 && !mKillNow.load(std::memory_order_acquire))
+        mDevice->renderSamples(buffer.data(), static_cast<uint>(buffer.size() / frameSize),
+            frameStep);
+        while(!buffer.empty() && !mKillNow.load(std::memory_order_acquire))
         {
-            size_t wrote{sio_write(mSndHandle, WritePtr, len)};
+            size_t wrote{sio_write(mSndHandle, buffer.data(), buffer.size())};
             if(wrote == 0)
             {
                 ERR("sio_write failed\n");
                 mDevice->handleDisconnect("Failed to write playback samples");
                 break;
             }
-
-            len -= wrote;
-            WritePtr += wrote;
+            buffer = buffer.subspan(wrote);
         }
     }
 
@@ -136,25 +132,11 @@ void SndioPlayback::open(const char *name)
 
 bool SndioPlayback::reset()
 {
-    sio_par par;
-    sio_initpar(&par);
+    SioPar par;
 
-    par.rate = mDevice->Frequency;
-    switch(mDevice->FmtChans)
-    {
-    case DevFmtMono   : par.pchan = 1; break;
-    case DevFmtQuad   : par.pchan = 4; break;
-    case DevFmtX51Rear: // fall-through - "Similar to 5.1, except using rear channels instead of sides"
-    case DevFmtX51    : par.pchan = 6; break;
-    case DevFmtX61    : par.pchan = 7; break;
-    case DevFmtX71    : par.pchan = 8; break;
-
-    // fall back to stereo for Ambi3D
-    case DevFmtAmbi3D : // fall-through
-    case DevFmtStereo : par.pchan = 2; break;
-    }
-
-    switch(mDevice->FmtType)
+    auto tryfmt = mDevice->FmtType;
+retry_params:
+    switch(tryfmt)
     {
     case DevFmtByte:
         par.bits = 8;
@@ -164,7 +146,6 @@ bool SndioPlayback::reset()
         par.bits = 8;
         par.sig = 0;
         break;
-    case DevFmtFloat:
     case DevFmtShort:
         par.bits = 16;
         par.sig = 1;
@@ -173,6 +154,7 @@ bool SndioPlayback::reset()
         par.bits = 16;
         par.sig = 0;
         break;
+    case DevFmtFloat:
     case DevFmtInt:
         par.bits = 32;
         par.sig = 1;
@@ -182,70 +164,62 @@ bool SndioPlayback::reset()
         par.sig = 0;
         break;
     }
+    par.bps = SIO_BPS(par.bits);
     par.le = SIO_LE_NATIVE;
 
+    par.rate = mDevice->Frequency;
+    par.pchan = mDevice->channelsFromFmt();
+
     par.round = mDevice->UpdateSize;
     par.appbufsz = mDevice->BufferSize - mDevice->UpdateSize;
     if(!par.appbufsz) par.appbufsz = mDevice->UpdateSize;
 
-    if(!sio_setpar(mSndHandle, &par) || !sio_getpar(mSndHandle, &par))
-    {
-        ERR("Failed to set device parameters\n");
-        return false;
-    }
-
-    if(par.bits != par.bps*8)
-    {
-        ERR("Padded samples not supported (%u of %u bits)\n", par.bits, par.bps*8);
-        return false;
-    }
-    if(par.le != SIO_LE_NATIVE)
-    {
-        ERR("Non-native-endian samples not supported (got %s-endian)\n",
-            par.le ? "little" : "big");
-        return false;
-    }
-
-    mDevice->Frequency = par.rate;
-
-    if(par.pchan < 2)
-    {
-        if(mDevice->FmtChans != DevFmtMono)
-        {
-            WARN("Got %u channel for %s\n", par.pchan, DevFmtChannelsString(mDevice->FmtChans));
-            mDevice->FmtChans = DevFmtMono;
-        }
+    try {
+        if(!sio_setpar(mSndHandle, &par))
+            throw al::backend_exception{al::backend_error::DeviceError,
+                "Failed to set device parameters"};
+
+        par.clear();
+        if(!sio_getpar(mSndHandle, &par))
+            throw al::backend_exception{al::backend_error::DeviceError,
+                "Failed to get device parameters"};
+
+        if(par.bps > 1 && par.le != SIO_LE_NATIVE)
+            throw al::backend_exception{al::backend_error::DeviceError,
+                "%s-endian samples not supported", par.le ? "Little" : "Big"};
+        if(par.bits < par.bps*8 && !par.msb)
+            throw al::backend_exception{al::backend_error::DeviceError,
+                "MSB-padded samples not supported (%u of %u bits)", par.bits, par.bps*8};
+        if(par.pchan < 1)
+            throw al::backend_exception{al::backend_error::DeviceError,
+                "No playback channels on device"};
     }
-    else if((par.pchan == 2 && mDevice->FmtChans != DevFmtStereo)
-        || par.pchan == 3
-        || (par.pchan == 4 && mDevice->FmtChans != DevFmtQuad)
-        || par.pchan == 5
-        || (par.pchan == 6 && mDevice->FmtChans != DevFmtX51 && mDevice->FmtChans != DevFmtX51Rear)
-        || (par.pchan == 7 && mDevice->FmtChans != DevFmtX61)
-        || (par.pchan == 8 && mDevice->FmtChans != DevFmtX71)
-        || par.pchan > 8)
-    {
-        WARN("Got %u channels for %s\n", par.pchan, DevFmtChannelsString(mDevice->FmtChans));
-        mDevice->FmtChans = DevFmtStereo;
+    catch(al::backend_exception &e) {
+        if(tryfmt == DevFmtShort)
+            throw;
+        tryfmt = DevFmtShort;
+        goto retry_params;
     }
 
-    if(par.bits == 8 && par.sig == 1)
-        mDevice->FmtType = DevFmtByte;
-    else if(par.bits == 8 && par.sig == 0)
-        mDevice->FmtType = DevFmtUByte;
-    else if(par.bits == 16 && par.sig == 1)
-        mDevice->FmtType = DevFmtShort;
-    else if(par.bits == 16 && par.sig == 0)
-        mDevice->FmtType = DevFmtUShort;
-    else if(par.bits == 32 && par.sig == 1)
-        mDevice->FmtType = DevFmtInt;
-    else if(par.bits == 32 && par.sig == 0)
-        mDevice->FmtType = DevFmtUInt;
+    if(par.bps == 1)
+        mDevice->FmtType = (par.sig==1) ? DevFmtByte : DevFmtUByte;
+    else if(par.bps == 2)
+        mDevice->FmtType = (par.sig==1) ? DevFmtShort : DevFmtUShort;
+    else if(par.bps == 4)
+        mDevice->FmtType = (par.sig==1) ? DevFmtInt : DevFmtUInt;
     else
+        throw al::backend_exception{al::backend_error::DeviceError,
+            "Unhandled sample format: %s %u-bit", (par.sig?"signed":"unsigned"), par.bps*8};
+
+    mFrameStep = par.pchan;
+    if(par.pchan != mDevice->channelsFromFmt())
     {
-        ERR("Unhandled sample format: %s %u-bit\n", (par.sig?"signed":"unsigned"), par.bits);
-        return false;
+        WARN("Got %u channel%s for %s\n", par.pchan, (par.pchan==1)?"":"s",
+            DevFmtChannelsString(mDevice->FmtChans));
+        if(par.pchan < 2) mDevice->FmtChans = DevFmtMono;
+        else mDevice->FmtChans = DevFmtStereo;
     }
+    mDevice->Frequency = par.rate;
 
     setDefaultChannelOrder();