From 207febef9924c8fa5391185e75d42a7ea480bb38 Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Mon, 10 Aug 2026 11:11:18 -0700
Subject: Chapter 31: Software Drawing, Time, and Graphical Games

Co-authored-by: Hsiang-Ying Fu <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: fuhsnn <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: Symious <14933944+symious@users.noreply.github.com>
Co-authored-by: Jun Kawasaki <jun784@gmail.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>
---
 src/main/c/simple_miniaudio.c | 123 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 src/main/c/simple_miniaudio.c

(limited to 'src/main/c/simple_miniaudio.c')

diff --git a/src/main/c/simple_miniaudio.c b/src/main/c/simple_miniaudio.c
new file mode 100644
index 00000000..03dbadd7
--- /dev/null
+++ b/src/main/c/simple_miniaudio.c
@@ -0,0 +1,123 @@
+#include "simple_audio.h"
+#define MA_NO_DECODING
+#define MA_NO_ENCODING
+#define MA_NO_RESOURCE_MANAGER
+#define MA_NO_NODE_GRAPH
+#define MA_NO_ENGINE
+#define MINIAUDIO_IMPLEMENTATION
+#include <miniaudio.h>
+#include <math.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#define RATE 48000
+#define SLOTS 32
+static ma_device device;
+static ma_mutex mutex;
+static int opened, active;
+static uint32_t cursor;
+static struct { int16_t *pcm; uint32_t count; } sounds[SLOTS];
+
+// Only native-owned immutable PCM is read on the audio thread. The lock covers
+// a bounded copy, never allocation, synthesis, device calls, or Simple code.
+static void output(ma_device *unused, void *out, const void *in, ma_uint32 frames) {
+    (void)unused; (void)in;
+    memset(out,0,frames*sizeof(int16_t));
+    ma_mutex_lock(&mutex);
+    if (active) {
+        uint32_t count=sounds[active].count-cursor;
+        if (count>frames) count=frames;
+        memcpy(out,sounds[active].pcm+cursor,count*sizeof(int16_t));
+        cursor+=count;
+        if (cursor==sounds[active].count) active=0;
+    }
+    ma_mutex_unlock(&mutex);
+}
+static int32_t load(const int16_t *pcm, uint32_t count) {
+    if (!opened || !pcm || !count || count>RATE*10) return -1;
+    int slot;
+    for (slot=4; slot<SLOTS && sounds[slot].pcm; ++slot) {}
+    if (slot==SLOTS) return -1;
+    int16_t *copy=malloc(count*sizeof(*copy));
+    if (!copy) return -1;
+    memcpy(copy,pcm,count*sizeof(*copy));
+    ma_mutex_lock(&mutex);
+    sounds[slot].pcm=copy; sounds[slot].count=count;
+    ma_mutex_unlock(&mutex);
+    return slot;
+}
+static int32_t play(int32_t sound) {
+    if (!opened || sound<=0 || sound>=SLOTS || !sounds[sound].pcm) return -1;
+    ma_mutex_lock(&mutex);
+    active=sound; cursor=0;
+    ma_mutex_unlock(&mutex);
+    return 0;
+}
+static int32_t stop(void) {
+    if (opened) { ma_mutex_lock(&mutex); active=0; ma_mutex_unlock(&mutex); }
+    return 0;
+}
+static int32_t playing(void) {
+    if (!opened) return 0;
+    ma_mutex_lock(&mutex);
+    int result=active!=0;
+    ma_mutex_unlock(&mutex);
+    return result;
+}
+static void close_audio(void) {
+    if (!opened) return;
+    ma_device_uninit(&device); // Joins callback before freeing buffers/mutex.
+    ma_mutex_uninit(&mutex);
+    for (int i=1;i<SLOTS;++i) {
+        free(sounds[i].pcm); sounds[i].pcm=NULL; sounds[i].count=0;
+    }
+    opened=0; active=0; cursor=0;
+}
+static int tone(int slot, int descending) {
+    uint32_t note=slot==1 ? RATE*7/100 : RATE*16/100;
+    int notes=slot==1 ? 1 : 3;
+    sounds[slot].count=note*notes;
+    sounds[slot].pcm=calloc(note*notes,sizeof(int16_t));
+    if (!sounds[slot].pcm) return -1;
+    const double pitches[3]={523.251,659.255,783.991};
+    for (int n=0;n<notes;++n) {
+        double hz=slot==1 ? 440.0 : pitches[descending ? 2-n : n];
+        for (uint32_t i=0;i<note;++i) {
+            double t=(double)i/note;
+            double envelope=sin(3.141592653589793*t);
+            sounds[slot].pcm[n*note+i]=(int16_t)(3200*envelope*envelope*sin(6.283185307179586*hz*i/RATE));
+        }
+    }
+    return 0;
+}
+static int32_t open_audio(void) {
+    if (opened) return 0;
+    if (ma_mutex_init(&mutex)!=MA_SUCCESS) return -1;
+    ma_device_config config=ma_device_config_init(ma_device_type_playback);
+    config.playback.format=ma_format_s16;
+    config.playback.channels=1;
+    config.sampleRate=RATE;
+    config.dataCallback=output;
+#ifdef SIMPLE_AUDIO_TEST_NULL
+    ma_backend backend=ma_backend_null;
+    ma_result result=ma_device_init_ex(&backend,1,NULL,&config,&device);
+#else
+    ma_result result=ma_device_init(NULL,&config,&device);
+#endif
+    if (result!=MA_SUCCESS) {
+        ma_mutex_uninit(&mutex);
+        fprintf(stderr,"Simple audio: no playback device (%d); continuing silently.\n",result);
+        return -1;
+    }
+    opened=1;
+    if (tone(1,0) || tone(2,0) || tone(3,1) || ma_device_start(&device)!=MA_SUCCESS) {
+        close_audio(); return -1;
+    }
+    return 0;
+}
+static const struct simple_audio_api api={SIMPLE_AUDIO_VERSION,open_audio,load,play,stop,playing,close_audio};
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+const struct simple_audio_api *simple_miniaudio_api(void) { return &api; }
-- 
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