IWMMXT-specific dsputils clear_blocks function.

patch by David Bateman, adb014 gmail com

Originally committed as revision 8632 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/armv4l/dsputil_iwmmxt.c

@@ -123,6 +123,25 @@ void add_pixels_clamped_iwmmxt(const DCTELEM *block, uint8_t *pixels, int line_s
         : "cc", "memory", "r12");
 }
 
+static void clear_blocks_iwmmxt(DCTELEM *blocks)
+{
+    __asm __volatile(
+                "wzero wr0                      \n\t"
+                "mov r1, #(128 * 6 / 32)        \n\t"
+                "1:                             \n\t"
+                "wstrd wr0, [%0]                \n\t"
+                "wstrd wr0, [%0, #8]            \n\t"
+                "wstrd wr0, [%0, #16]           \n\t"
+                "wstrd wr0, [%0, #24]           \n\t"
+                "subs r1, r1, #1                \n\t"
+                "add %0, %0, #32                \n\t"
+                "bne 1b                         \n\t"
+                : "+r"(blocks)
+                :
+                : "r1"
+        );
+}
+
 static void nop(uint8_t *block, const uint8_t *pixels, int line_size, int h)
 {
     return;
@@ -146,6 +165,8 @@ void dsputil_init_iwmmxt(DSPContext* c, AVCodecContext *avctx)
 
     c->add_pixels_clamped = add_pixels_clamped_iwmmxt;
 
+    c->clear_blocks = clear_blocks_iwmmxt;
+
     c->put_pixels_tab[0][0] = put_pixels16_iwmmxt;
     c->put_pixels_tab[0][1] = put_pixels16_x2_iwmmxt;
     c->put_pixels_tab[0][2] = put_pixels16_y2_iwmmxt;