Extend bit-buffer library with writing total byte

This is useful to write out a full byte. Note this cannot be done using simple
fwrite, as we need to consider the bit cursor.

bit-buffer.c

@@ -78,6 +78,29 @@ bb_write (struct BIT_BUFFER *buffer, int *bits, int size)
 }
 
 /*
+ * Write byte to file, taking bit pos into account.
+ */
+void
+bb_writebyte (struct BIT_BUFFER *buffer, byte byte)
+{
+  int i, shift_pos;
+  printf("-- %x\n", byte);
+  for (i = 0; i < BYTE_BIT; i++)
+    {
+      if (buffer->pos == BYTE_BIT)
+        bb_flush (buffer);
+
+      shift_pos = BYTE_BIT - buffer->pos - 1;
+      if (byte & (1 << (BYTE_BIT - 1 - i)))
+        buffer->bits |= (1 << shift_pos);
+      else
+        buffer->bits &= ~(1 << shift_pos);
+
+      (buffer->pos)++;
+    }
+}
+
+/*
  * Read bits from file.
  *
  * The return value must be freed after being used.

bit-buffer.h

@@ -14,4 +14,5 @@ typedef struct BIT_BUFFER
 void bb_init (struct BIT_BUFFER *buffer, FILE *fp);
 void bb_flush (struct BIT_BUFFER *buffer);
 void bb_write (struct BIT_BUFFER *buffer, int *bits, int size);
+void bb_writebyte (struct BIT_BUFFER *buffer, byte byte);
 int *bb_read (struct BIT_BUFFER *buffer, int size);