vlc_bits: Differentiate between writable bits stream and read only.

This fixes some const qualifier violation in modules.

include/vlc_bits.h

@@ -30,15 +30,25 @@
  */
 
 typedef struct bs_s
+{
+    const uint8_t *p_start;
+    const uint8_t *p;
+    const uint8_t *p_end;
+
+    unsigned     i_left;    /* i_count number of available bits */
+} bs_t;
+
+typedef struct bs_writable_s
 {
     uint8_t *p_start;
     uint8_t *p;
     uint8_t *p_end;
+    
+    unsigned     i_left;    /* i_count number of available bits */
+} bsw_t;
 
-    int     i_left;    /* i_count number of available bits */
-} bs_t;
 
-static inline void bs_init( bs_t *s, void *p_data, int i_data )
+static inline void bs_init( bs_t *s, const void *p_data, unsigned i_data )
 {
     s->p_start = p_data;
     s->p       = p_data;
@@ -141,25 +151,67 @@ static inline void bs_skip( bs_t *s, int i_count )
     }
 }
 
-static inline void bs_write( bs_t *s, int i_count, uint32_t i_bits )
+/*
+ * Writable bits stream
+ */
+static inline void bsw_init_writable( bsw_t *s, void *p_data, unsigned i_data )
+{
+    s->p_start = p_data;
+    s->p       = p_data;
+    s->p_end   = s->p + i_data;
+    s->i_left  = 8;
+}
+
+static inline bs_t * bs_from_writable( bsw_t *s )
+{
+    return (bs_t *)s;
+}
+
+static inline void bsw_skip( bsw_t *s, int count )
+{
+    return bs_skip(bs_from_writable(s), count);
+}
+
+static inline uint32_t bsw_show( bsw_t *s, int count )
+{
+    return bs_show(bs_from_writable(s), count);
+}
+
+static inline uint32_t bsw_read1( bsw_t *s )
+{
+    return bs_read1(bs_from_writable(s));
+}
+
+static inline uint32_t bsw_read( bsw_t *s, int count )
+{
+    return bs_read(bs_from_writable(s), count);
+}
+
+static inline int bsw_pos( bsw_t *s )
+{
+    return bs_pos(bs_from_writable(s));
+}
+
+static inline int bsw_eof( bsw_t *s )
+{
+    return bs_eof(bs_from_writable(s));
+}
+
+
+static inline void bsw_write( bsw_t *s, int i_count, uint32_t i_bits )
 {
     while( i_count > 0 )
     {
         if( s->p >= s->p_end )
-        {
             break;
-        }
 
         i_count--;
 
         if( ( i_bits >> i_count )&0x01 )
-        {
             *s->p |= 1 << ( s->i_left - 1 );
-        }
         else
-        {
             *s->p &= ~( 1 << ( s->i_left - 1 ) );
-        }
+
         s->i_left--;
         if( s->i_left == 0 )
         {
@@ -169,7 +221,7 @@ static inline void bs_write( bs_t *s, int i_count, uint32_t i_bits )
     }
 }
 
-static inline void bs_align( bs_t *s )
+static inline void bsw_align( bsw_t *s )
 {
     if( s->i_left != 8 )
     {
@@ -178,20 +230,16 @@ static inline void bs_align( bs_t *s )
     }
 }
 
-static inline void bs_align_0( bs_t *s )
+static inline void bsw_align_0( bsw_t *s )
 {
     if( s->i_left != 8 )
-    {
-        bs_write( s, s->i_left, 0 );
-    }
+        bsw_write( s, s->i_left, 0 );
 }
 
-static inline void bs_align_1( bs_t *s )
+static inline void bsw_align_1( bsw_t *s )
 {
     while( s->i_left != 8 )
-    {
-        bs_write( s, 1, 1 );
-    }
+        bsw_write( s, 1, 1 );
 }
 
 #endif

modules/codec/cvdsub.c

@@ -573,9 +573,9 @@ static void RenderImage( decoder_t *p_dec, block_t *p_data,
     int i_field;            /* The subtitles are interlaced */
     int i_row, i_column;    /* scanline row/column number */
     uint8_t i_color, i_count;
-    bs_t bs;
+    bsw_t bsw;
 
-    bs_init( &bs, p_data->p_buffer + p_sys->i_image_offset,
+    bsw_init_writable( &bsw, p_data->p_buffer + p_sys->i_image_offset,
              p_data->i_buffer - p_sys->i_image_offset );
 
     for( i_field = 0; i_field < 2; i_field++ )
@@ -584,12 +584,12 @@ static void RenderImage( decoder_t *p_dec, block_t *p_data,
         {
             for( i_column = 0; i_column < p_sys->i_width; i_column++ )
             {
-                uint8_t i_val = bs_read( &bs, 4 );
+                uint8_t i_val = bsw_read( &bsw, 4 );
 
                 if( i_val == 0 )
                 {
                     /* Fill the rest of the line with next color */
-                    i_color = bs_read( &bs, 4 );
+                    i_color = bsw_read( &bsw, 4 );
 
                     memset( &p_dest[i_row * p_region->p_picture->Y_PITCH +
                                     i_column], i_color,
@@ -612,7 +612,7 @@ static void RenderImage( decoder_t *p_dec, block_t *p_data,
                 }
             }
 
-            bs_align( &bs );
+            bsw_align( &bsw );
         }
     }
 }

modules/codec/svcdsub.c

@@ -546,9 +546,9 @@ static void SVCDSubRenderImage( decoder_t *p_dec, block_t *p_data,
     int i_field;            /* The subtitles are interlaced */
     int i_row, i_column;    /* scanline row/column number */
     uint8_t i_color, i_count;
-    bs_t bs;
+    bsw_t bs;
 
-    bs_init( &bs, p_data->p_buffer + p_sys->i_image_offset,
+    bsw_init_writable( &bs, p_data->p_buffer + p_sys->i_image_offset,
              p_data->i_buffer - p_sys->i_image_offset );
 
     for( i_field = 0; i_field < 2; i_field++ )
@@ -557,8 +557,8 @@ static void SVCDSubRenderImage( decoder_t *p_dec, block_t *p_data,
         {
             for( i_column = 0; i_column < p_sys->i_width; i_column++ )
             {
-                i_color = bs_read( &bs, 2 );
-                if( i_color == 0 && (i_count = bs_read( &bs, 2 )) )
+                i_color = bsw_read( &bs, 2 );
+                if( i_color == 0 && (i_count = bsw_read( &bs, 2 )) )
                 {
                     i_count = __MIN( i_count, p_sys->i_width - i_column );
                     memset( &p_dest[i_row * p_region->p_picture->Y_PITCH +
@@ -570,11 +570,11 @@ static void SVCDSubRenderImage( decoder_t *p_dec, block_t *p_data,
                 p_dest[i_row * p_region->p_picture->Y_PITCH + i_column] = i_color;
             }
 
-            bs_align( &bs );
+            bsw_align( &bs );
         }
 
         /* odd field */
-        bs_init( &bs, p_data->p_buffer + p_sys->i_image_offset +
+        bsw_init_writable( &bs, p_data->p_buffer + p_sys->i_image_offset +
                  p_sys->second_field_offset,
                  p_data->i_buffer - p_sys->i_image_offset -
                  p_sys->second_field_offset );