before starting pa3

221220000 张三
Linux zzy 5.15.146.1-microsoft-standard-WSL2 #1 SMP Thu Jan 11 04:09:03 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux
 15:15:55 up 4 days, 10:21,  1 user,  load average: 0.95, 0.97, 0.79

abstract-machine/am/src/platform/nemu/ioe/audio.c

@@ -10,6 +10,7 @@
 
 static uint32_t audio_write = 0;
 static uint32_t audio_sbuf_size;
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
 
 void __am_audio_init() {
 }
@@ -39,16 +40,15 @@ void __am_audio_play(AM_AUDIO_PLAY_T *ctl) {
   while (cnt) {
     // lock sbuf
     outl(AUDIO_INIT_ADDR, 2);
-    for (; i < cnt; i++) {
-      if (inl(AUDIO_COUNT_ADDR) == audio_sbuf_size) {
-        i--;
-        break;
-      } else {
-        outb(AUDIO_SBUF_ADDR + audio_write, ((uint8_t*)ctl->buf.start)[i]);
-        audio_write = (audio_write + 1) % audio_sbuf_size;
-        outl(AUDIO_COUNT_ADDR, inl(AUDIO_COUNT_ADDR) + 1);
-      }
+
+    int last = audio_sbuf_size - inl(AUDIO_COUNT_ADDR);
+    int write_num = MIN(last, cnt);
+    for (int j = i; j < write_num; i ++, j ++) {
+      outb(AUDIO_SBUF_ADDR + audio_write, ((uint8_t*)(ctl->buf.start))[i]);
+      audio_write = (audio_write + 1) % audio_sbuf_size;
     }
+    cnt -= write_num;
+    outl(AUDIO_COUNT_ADDR, inl(AUDIO_COUNT_ADDR) + write_num);
     // unlock sbuf
     outl(AUDIO_INIT_ADDR, 0);
   }

nemu/src/device/audio.c

@@ -43,7 +43,7 @@ static void audio_callback(void *userdata, uint8_t *stream, int len) {
   uint32_t read_cnt = MIN(count, len);
   uint32_t to_end_cnt = CONFIG_SB_SIZE - pos_read;
   int32_t out_bound_cnt = read_cnt - to_end_cnt;
-  memset(stream, 0, len);
+  // memset(stream, 0, len);
   if (out_bound_cnt > 0) {
     memcpy(stream, sbuf + pos_read, to_end_cnt);
     memcpy(stream + to_end_cnt, sbuf, out_bound_cnt);
@@ -52,7 +52,7 @@ static void audio_callback(void *userdata, uint8_t *stream, int len) {
   }
   pos_read += read_cnt;
   pos_read %= CONFIG_SB_SIZE;
-  // if (len > read_cnt) memset(stream + read_cnt, 0, len - read_cnt);
+  if (len > read_cnt) memset(stream + read_cnt, 0, len - read_cnt);
   count -= read_cnt;
   audio_count = count;
   mtx_unlock(&mtx_audio);