1 files changed, 48 insertions, 0 deletions
diff --git a/kernel/audio.c b/kernel/audio.c
index 60df1f3..d8fcd3c 100644
--- a/kernel/audio.c
+++ b/kernel/audio.c
@@ -1,5 +1,7 @@
 // TODO: This should support multiple audio sources.
+#include <assert.h>
 #include <audio.h>
+#include <ctype.h>
 #include <drivers/ac97.h>
 #include <errno.h>
 #include <fs/devfs.h>
@@ -20,9 +22,55 @@ int audio_can_write(vfs_inode_t *inode) {
   return ac97_can_write();
 }
 
+int volume_write(u8 *buffer, u64 offset, u64 len, vfs_fd_t *fd) {
+  (void)offset;
+  (void)fd;
+  int volume = 0;
+
+  size_t i = 0;
+  for (; i < len; i++) {
+    u8 c = buffer[i];
+    if (!isdigit(c)) {
+      break;
+    }
+    volume *= 10;
+    volume += c - '0';
+    if (volume > 100) {
+      volume = 100;
+      break;
+    }
+  }
+  if (0 == i) {
+    return 0;
+  }
+  ac97_set_volume(volume);
+  return i;
+}
+
+int volume_read(u8 *buffer, u64 offset, u64 len, vfs_fd_t *fd) {
+  if (offset > 0) {
+    return 0;
+  }
+  (void)fd;
+  if (len < 3) {
+    return 0;
+  }
+  int volume = ac97_get_volume();
+  assert(volume <= 100);
+  if (volume == 100) {
+    memcpy(buffer, "100", 3);
+    return 3;
+  }
+  buffer[1] = (volume % 10) + '0';
+  buffer[0] = ((volume - (volume % 10)) / 10) + '0';
+  return 2;
+}
+
 static int add_files(void) {
   devfs_add_file("/audio", NULL, audio_write, NULL, NULL, audio_can_write,
                  FS_TYPE_CHAR_DEVICE);
+  devfs_add_file("/volume", volume_read, volume_write, NULL, always_has_data,
+                 always_can_write, FS_TYPE_BLOCK_DEVICE);
   return 1;
 }