From 312ab52ecae596a3776d7e789a09e85a50012f2e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Bourdeauducq?= <sb@m-labs.hk>
Date: Thu, 26 Dec 2024 17:33:59 +0800
Subject: [PATCH] nonblocking

---
 sndlock.cpp | 46 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/sndlock.cpp b/sndlock.cpp
index c4f3b77..01b6b88 100644
--- a/sndlock.cpp
+++ b/sndlock.cpp
@@ -4,6 +4,7 @@
 
 #include <GLFW/glfw3.h>
 #include <sndio.h>
+#include <poll.h>
 #include <math.h>
 
 #include "imgui.h"
@@ -24,7 +25,7 @@ static void dsp_thread()
     struct sio_hdl *hdl;
     struct sio_par par;
 
-    hdl = sio_open(SIO_DEVANY, SIO_PLAY, 0);
+    hdl = sio_open(SIO_DEVANY, SIO_PLAY, 1);
     if(hdl == nullptr) {
         std::cerr << "failed to open sound device" << std::endl;
         return;
@@ -35,11 +36,17 @@ static void dsp_thread()
     par.pchan = SND_PCHAN;
     par.rate = SND_RATE;
     par.le = SIO_LE_NATIVE;
+    par.xrun = SIO_ERROR;
     if(!sio_setpar(hdl, &par)) {
         std::cerr << "failed to set sound device parameters" << std::endl;
         sio_close(hdl);
         return;
     }
+    if(!sio_getpar(hdl, &par)) {
+        std::cerr << "failed to get back sound device parameters" << std::endl;
+        sio_close(hdl);
+        return;
+    }
 
     if(!sio_start(hdl)) {
         std::cerr << "failed to start sound device" << std::endl;
@@ -48,18 +55,33 @@ static void dsp_thread()
     }
 
     uint32_t phase = 0;
-    int16_t buf[SND_BUFLEN*SND_PCHAN];
+
+    int16_t buf_out[SND_BUFLEN*SND_PCHAN];
+    size_t buf_out_idx = SND_BUFLEN*SND_PCHAN;
+    nfds_t nfds = sio_nfds(hdl);
+    struct pollfd pfd[nfds];
     while(!shutdown_threads) {
-        uint32_t ftw = frequency*(float)UINT32_MAX/SND_RATE;
-        for(int i=0;i<SND_BUFLEN;i++) {
-            buf[2*i] = buf[2*i+1] = (INT16_MAX-1)*sin(phase*2.0f*(float)M_PI/(float)UINT32_MAX);
-            phase += ftw;
-        }
-        if(!sio_write(hdl, buf, SND_BUFLEN*(SND_BITS/8)*SND_PCHAN)) {
-            std::cerr << "failed to write to sound device" << std::endl;
-            sio_stop(hdl);
-            sio_close(hdl);
-            return;
+        sio_pollfd(hdl, pfd, POLLOUT);
+        poll(pfd, nfds, INFTIM);
+        int revents = sio_revents(hdl, pfd);
+
+        if(revents & POLLOUT) {
+            uint32_t ftw = frequency*(float)UINT32_MAX/SND_RATE;
+            if(buf_out_idx == SND_BUFLEN*SND_PCHAN) {
+                for(int i=0;i<SND_BUFLEN;i++) {
+                    buf_out[2*i] = buf_out[2*i+1] = (INT16_MAX-1)*sin(phase*2.0f*(float)M_PI/(float)UINT32_MAX);
+                    phase += ftw;
+                }
+                buf_out_idx = 0;
+            }
+            size_t written = sio_write(hdl, &buf_out[buf_out_idx], sizeof(buf_out) - buf_out_idx*sizeof(buf_out[0]));
+            buf_out_idx += written/sizeof(buf_out[0]);
+            if(!written) {
+                std::cerr << "failed to write to sound device" << std::endl;
+                sio_stop(hdl);
+                sio_close(hdl);
+                return;
+            }
         }
     }