seperated out the C-based VP3 DSP functions into a different file; also

ported the MMX-optimized versions of those functions

Originally committed as revision 2855 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 652 insertions, 0 deletions

diff --git a/libavcodec/i386/vp3dsp_mmx.c b/libavcodec/i386/vp3dsp_mmx.c
new file mode 100644
index 0000000000..59020466f4
--- /dev/null
+++ b/libavcodec/i386/vp3dsp_mmx.c
@@ -0,0 +1,652 @@
+/*
+ * Copyright (C) 2004 the ffmpeg project
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/**
+ * @file vp3dsp_mmx.c
+ * MMX-optimized functions cribbed from the original VP3 source code.
+ */
+
+#include "../dsputil.h"
+#include "mmx.h"
+
+#define IdctAdjustBeforeShift 8
+
+/* (12 * 4) 2-byte memory locations ( = 96 bytes total)
+ * idct_constants[0..15] = Mask table (M(I))
+ * idct_constants[16..43] = Cosine table (C(I))
+ * idct_constants[44..47] = 8
+ */
+static uint16_t idct_constants[(4 + 7 + 1) * 4];
+static uint16_t idct_cosine_table[7] = {
+    64277, 60547, 54491, 46341, 36410, 25080, 12785
+};
+
+#define r0 mm0
+#define r1 mm1
+#define r2 mm2
+#define r3 mm3
+#define r4 mm4
+#define r5 mm5
+#define r6 mm6
+#define r7 mm7
+
+/* from original comments: The Macro does IDct on 4 1-D Dcts */
+#define BeginIDCT() \
+    movq_m2r(*I(3), r2); \
+    movq_m2r(*C(3), r6); \
+    movq_r2r(r2, r4); \
+    movq_m2r(*J(5), r7); \
+    pmulhw_r2r(r6, r4); \
+    movq_m2r(*C(5), r1); \
+    pmulhw_r2r(r7, r6); \
+    movq_r2r(r1, r5); \
+    pmulhw_r2r(r2, r1); \
+    movq_m2r(*I(1), r3); \
+    pmulhw_r2r(r7, r5); \
+    movq_m2r(*C(1), r0); \
+    paddw_r2r(r2, r4); \
+    paddw_r2r(r7, r6); \
+    paddw_r2r(r1, r2); \
+    movq_m2r(*J(7), r1); \
+    paddw_r2r(r5, r7); \
+    movq_r2r(r0, r5); \
+    pmulhw_r2r(r3, r0); \
+    paddsw_r2r(r7, r4); \
+    pmulhw_r2r(r1, r5); \
+    movq_m2r(*C(7), r7); \
+    psubsw_r2r(r2, r6); \
+    paddw_r2r(r3, r0); \
+    pmulhw_r2r(r7, r3); \
+    movq_m2r(*I(2), r2); \
+    pmulhw_r2r(r1, r7); \
+    paddw_r2r(r1, r5); \
+    movq_r2r(r2, r1); \
+    pmulhw_m2r(*C(2), r2); \
+    psubsw_r2r(r5, r3); \
+    movq_m2r(*J(6), r5); \
+    paddsw_r2r(r7, r0); \
+    movq_r2r(r5, r7); \
+    psubsw_r2r(r4, r0); \
+    pmulhw_m2r(*C(2), r5); \
+    paddw_r2r(r1, r2); \
+    pmulhw_m2r(*C(6), r1); \
+    paddsw_r2r(r4, r4); \
+    paddsw_r2r(r0, r4); \
+    psubsw_r2r(r6, r3); \
+    paddw_r2r(r7, r5); \
+    paddsw_r2r(r6, r6); \
+    pmulhw_m2r(*C(6), r7); \
+    paddsw_r2r(r3, r6); \
+    movq_r2m(r4, *I(1)); \
+    psubsw_r2r(r5, r1); \
+    movq_m2r(*C(4), r4); \
+    movq_r2r(r3, r5); \
+    pmulhw_r2r(r4, r3); \
+    paddsw_r2r(r2, r7); \
+    movq_r2m(r6, *I(2)); \
+    movq_r2r(r0, r2); \
+    movq_m2r(*I(0), r6); \
+    pmulhw_r2r(r4, r0); \
+    paddw_r2r(r3, r5); \
+    movq_m2r(*J(4), r3); \
+    psubsw_r2r(r1, r5); \
+    paddw_r2r(r0, r2); \
+    psubsw_r2r(r3, r6); \
+    movq_r2r(r6, r0); \
+    pmulhw_r2r(r4, r6); \
+    paddsw_r2r(r3, r3); \
+    paddsw_r2r(r1, r1); \
+    paddsw_r2r(r0, r3); \
+    paddsw_r2r(r5, r1); \
+    pmulhw_r2r(r3, r4); \
+    paddsw_r2r(r0, r6); \
+    psubsw_r2r(r2, r6); \
+    paddsw_r2r(r2, r2); \
+    movq_m2r(*I(1), r0); \
+    paddsw_r2r(r6, r2); \
+    paddw_r2r(r3, r4); \
+    psubsw_r2r(r1, r2);
+
+/* RowIDCT gets ready to transpose */
+#define RowIDCT() \
+    \
+    BeginIDCT() \
+    \
+    movq_m2r(*I(2), r3); \
+    psubsw_r2r(r7, r4); \
+    paddsw_r2r(r1, r1); \
+    paddsw_r2r(r7, r7); \
+    paddsw_r2r(r2, r1); \
+    paddsw_r2r(r4, r7); \
+    psubsw_r2r(r3, r4); \
+    psubsw_r2r(r5, r6); \
+    paddsw_r2r(r5, r5); \
+    paddsw_r2r(r4, r3); \
+    paddsw_r2r(r6, r5); \
+    psubsw_r2r(r0, r7); \
+    paddsw_r2r(r0, r0); \
+    movq_r2m(r1, *I(1)); \
+    paddsw_r2r(r7, r0);
+
+/* Column IDCT normalizes and stores final results */
+#define ColumnIDCT() \
+    \
+    BeginIDCT() \
+    \
+    paddsw_m2r(*Eight, r2); \
+    paddsw_r2r(r1, r1); \
+    paddsw_r2r(r2, r1); \
+    psraw_i2r(4, r2); \
+    psubsw_r2r(r7, r4); \
+    psraw_i2r(4, r1); \
+    movq_m2r(*I(2), r3); \
+    paddsw_r2r(r7, r7); \
+    movq_r2m(r2, *I(2)); \
+    paddsw_r2r(r4, r7); \
+    movq_r2m(r1, *I(1)); \
+    psubsw_r2r(r3, r4); \
+    paddsw_m2r(*Eight, r4); \
+    paddsw_r2r(r3, r3); \
+    paddsw_r2r(r4, r3); \
+    psraw_i2r(4, r4); \
+    psubsw_r2r(r5, r6); \
+    psraw_i2r(4, r3); \
+    paddsw_m2r(*Eight, r6); \
+    paddsw_r2r(r5, r5); \
+    paddsw_r2r(r6, r5); \
+    psraw_i2r(4, r6); \
+    movq_r2m(r4, *J(4)); \
+    psraw_i2r(4, r5); \
+    movq_r2m(r3, *I(3)); \
+    psubsw_r2r(r0, r7); \
+    paddsw_m2r(*Eight, r7); \
+    paddsw_r2r(r0, r0); \
+    paddsw_r2r(r7, r0); \
+    psraw_i2r(4, r7); \
+    movq_r2m(r6, *J(6)); \
+    psraw_i2r(4, r0); \
+    movq_r2m(r5, *J(5)); \
+    movq_r2m(r7, *J(7)); \
+    movq_r2m(r0, *I(0));
+
+
+/* Following macro does two 4x4 transposes in place.
+
+  At entry (we assume):
+
+        r0 = a3 a2 a1 a0
+        I(1) = b3 b2 b1 b0
+        r2 = c3 c2 c1 c0
+        r3 = d3 d2 d1 d0
+
+        r4 = e3 e2 e1 e0
+        r5 = f3 f2 f1 f0
+        r6 = g3 g2 g1 g0
+        r7 = h3 h2 h1 h0
+
+   At exit, we have:
+
+        I(0) = d0 c0 b0 a0
+        I(1) = d1 c1 b1 a1
+        I(2) = d2 c2 b2 a2
+        I(3) = d3 c3 b3 a3
+
+        J(4) = h0 g0 f0 e0
+        J(5) = h1 g1 f1 e1
+        J(6) = h2 g2 f2 e2
+        J(7) = h3 g3 f3 e3
+
+   I(0) I(1) I(2) I(3)  is the transpose of r0 I(1) r2 r3.
+   J(4) J(5) J(6) J(7)  is the transpose of r4 r5 r6 r7.
+
+   Since r1 is free at entry, we calculate the Js first. */
+
+#define Transpose() \
+    movq_r2r(r4, r1); \
+    punpcklwd_r2r(r5, r4); \
+    movq_r2m(r0, *I(0)); \
+    punpckhwd_r2r(r5, r1); \
+    movq_r2r(r6, r0); \
+    punpcklwd_r2r(r7, r6); \
+    movq_r2r(r4, r5); \
+    punpckldq_r2r(r6, r4); \
+    punpckhdq_r2r(r6, r5); \
+    movq_r2r(r1, r6); \
+    movq_r2m(r4, *J(4)); \
+    punpckhwd_r2r(r7, r0); \
+    movq_r2m(r5, *J(5)); \
+    punpckhdq_r2r(r0, r6); \
+    movq_m2r(*I(0), r4); \
+    punpckldq_r2r(r0, r1); \
+    movq_m2r(*I(1), r5); \
+    movq_r2r(r4, r0); \
+    movq_r2m(r6, *J(7)); \
+    punpcklwd_r2r(r5, r0); \
+    movq_r2m(r1, *J(6)); \
+    punpckhwd_r2r(r5, r4); \
+    movq_r2r(r2, r5); \
+    punpcklwd_r2r(r3, r2); \
+    movq_r2r(r0, r1); \
+    punpckldq_r2r(r2, r0); \
+    punpckhdq_r2r(r2, r1); \
+    movq_r2r(r4, r2); \
+    movq_r2m(r0, *I(0)); \
+    punpckhwd_r2r(r3, r5); \
+    movq_r2m(r1, *I(1)); \
+    punpckhdq_r2r(r5, r4); \
+    punpckldq_r2r(r5, r2); \
+    movq_r2m(r4, *I(3)); \
+    movq_r2m(r2, *I(2));
+
+
+void vp3_dsp_init_mmx(void)
+{
+    int j = 16;
+    uint16_t *p;
+
+    do {
+        idct_constants[--j] = 0;
+    } while (j);
+
+    idct_constants[0]  = idct_constants[5] = 
+    idct_constants[10] = idct_constants[15] = 65535;
+
+    j = 1;
+    do {
+        p = idct_constants + ((j + 3) << 2);
+        p[0] = p[1] = p[2] = p[3] = idct_cosine_table[j - 1];
+    } while (++j <= 7);
+
+    idct_constants[44] = idct_constants[45] = 
+    idct_constants[46] = idct_constants[47] = IdctAdjustBeforeShift;
+}
+
+static void vp3_idct_mmx(int16_t *input_data, int16_t *dequant_matrix,
+     int16_t *output_data)
+{
+    /* eax = quantized input
+     * ebx = dequantizer matrix
+     * ecx = IDCT constants
+     *  M(I) = ecx + MaskOffset(0) + I * 8
+     *  C(I) = ecx + CosineOffset(32) + (I-1) * 8
+     * edx = output
+     * r0..r7 = mm0..mm7
+     */
+
+#define M(x) (idct_constants + x * 4)
+#define C(x) (idct_constants + 16 + (x - 1) * 4)
+#define Eight (idct_constants + 44)
+
+    movq_m2r(*input_data, r0);
+    pmullw_m2r(*dequant_matrix, r0);
+    movq_m2r(*(input_data + 8), r1);
+    pmullw_m2r(*(dequant_matrix + 8), r1);
+    movq_m2r(*M(0), r2);
+    movq_r2r(r0, r3);
+    movq_m2r(*(input_data + 4), r4);
+    psrlq_i2r(16, r0);
+    pmullw_m2r(*(dequant_matrix + 4), r4);
+    pand_r2r(r2, r3);
+    movq_r2r(r0, r5);
+    movq_r2r(r1, r6);
+    pand_r2r(r2, r5);
+    psllq_i2r(32, r6);
+    movq_m2r(*M(3), r7);
+    pxor_r2r(r5, r0);
+    pand_r2r(r6, r7);
+    por_r2r(r3, r0);
+    pxor_r2r(r7, r6);
+    por_r2r(r7, r0);
+    movq_m2r(*M(3), r7);
+    movq_r2r(r4, r3);
+    movq_r2m(r0, *output_data);
+
+    pand_r2r(r2, r3);
+    movq_m2r(*(input_data + 16), r0);
+    psllq_i2r(16, r3);
+    pmullw_m2r(*(dequant_matrix + 16), r0);
+    pand_r2r(r1, r7);
+    por_r2r(r3, r5);
+    por_r2r(r6, r7);
+    movq_m2r(*(input_data + 12), r3);
+    por_r2r(r5, r7);
+    pmullw_m2r(*(dequant_matrix + 12), r3);
+    psrlq_i2r(16, r4);
+    movq_r2m(r7, *(output_data + 8));
+
+    movq_r2r(r4, r5);
+    movq_r2r(r0, r7);
+    psrlq_i2r(16, r4);
+    psrlq_i2r(48, r7);
+    movq_r2r(r2, r6);
+    pand_r2r(r2, r5);
+    pand_r2r(r4, r6);
+    movq_r2m(r7, *(output_data + 40));
+
+    pxor_r2r(r6, r4);
+    psrlq_i2r(32, r1);
+    por_r2r(r5, r4);
+    movq_m2r(*M(3), r7);
+    pand_r2r(r2, r1);
+    movq_m2r(*(input_data + 24), r5);
+    psllq_i2r(16, r0);
+    pmullw_m2r(*(dequant_matrix + 24), r5);
+    pand_r2r(r0, r7);
+    movq_r2m(r1, *(output_data + 32));
+
+    por_r2r(r4, r7);
+    movq_r2r(r3, r4);
+    pand_r2r(r2, r3);
+    movq_m2r(*M(2), r1);
+    psllq_i2r(32, r3);
+    por_r2r(r3, r7);
+    movq_r2r(r5, r3);
+    psllq_i2r(48, r3);
+    pand_r2r(r0, r1);
+    movq_r2m(r7, *(output_data + 16));
+
+    por_r2r(r3, r6);
+    movq_m2r(*M(1), r7);
+    por_r2r(r1, r6);
+    movq_m2r(*(input_data + 28), r1);
+    pand_r2r(r4, r7);
+    pmullw_m2r(*(dequant_matrix + 28), r1);
+    por_r2r(r6, r7);
+    pand_m2r(*M(1), r0);
+    psrlq_i2r(32, r4);
+    movq_r2m(r7, *(output_data + 24));
+
+    movq_r2r(r4, r6);
+    movq_m2r(*M(3), r7);
+    pand_r2r(r2, r4);
+    movq_m2r(*M(1), r3);
+    pand_r2r(r1, r7);
+    pand_r2r(r5, r3);
+    por_r2r(r4, r0);
+    psllq_i2r(16, r3);
+    por_r2r(r0, r7);
+    movq_m2r(*M(2), r4);
+    por_r2r(r3, r7);
+    movq_m2r(*(input_data + 40), r0);
+    movq_r2r(r4, r3);
+    pmullw_m2r(*(dequant_matrix + 40), r0);
+    pand_r2r(r5, r4);
+    movq_r2m(r7, *(output_data + 4));
+
+    por_r2r(r4, r6);
+    movq_r2r(r3, r4);
+    psrlq_i2r(16, r6);
+    movq_r2r(r0, r7);
+    pand_r2r(r1, r4);
+    psllq_i2r(48, r7);
+    por_r2r(r4, r6);
+    movq_m2r(*(input_data + 44), r4);
+    por_r2r(r6, r7);
+    pmullw_m2r(*(dequant_matrix + 44), r4);
+    psrlq_i2r(16, r3);
+    movq_r2m(r7, *(output_data + 12));
+
+    pand_r2r(r1, r3);
+    psrlq_i2r(48, r5);
+    pand_r2r(r2, r1);
+    movq_m2r(*(input_data + 52), r6);
+    por_r2r(r3, r5);
+    pmullw_m2r(*(input_data + 52), r6);
+    psrlq_i2r(16, r0);
+    movq_r2r(r4, r7);
+    movq_r2r(r2, r3);
+    psllq_i2r(48, r7);
+    pand_r2r(r0, r3);
+    pxor_r2r(r3, r0);
+    psllq_i2r(32, r3);
+    por_r2r(r5, r7);
+    movq_r2r(r6, r5);
+    pand_m2r(*M(1), r6);
+    por_r2r(r3, r7);
+    psllq_i2r(32, r6);
+    por_r2r(r1, r0);
+    movq_r2m(r7, *(output_data + 20));
+
+    por_r2r(r6, r0);
+    movq_m2r(*(input_data + 60), r7);
+    movq_r2r(r5, r6);
+    pmullw_m2r(*(input_data + 60), r7);
+    psrlq_i2r(32, r5);
+    pand_r2r(r2, r6);
+    movq_r2r(r5, r1);
+    movq_r2m(r0, *(output_data + 28));
+
+    pand_r2r(r2, r1);
+    movq_m2r(*(input_data + 56), r0);
+    movq_r2r(r7, r3);
+    pmullw_m2r(*(dequant_matrix + 56), r0);
+    psllq_i2r(16, r3);
+    pand_m2r(*M(3), r7);
+    pxor_r2r(r1, r5);
+    por_r2r(r5, r6);
+    movq_r2r(r3, r5);
+    pand_m2r(*M(3), r5);
+    por_r2r(r1, r7);
+    movq_m2r(*(input_data + 48), r1);
+    pxor_r2r(r5, r3);
+    pmullw_m2r(*(dequant_matrix + 48), r1);
+    por_r2r(r3, r7);
+    por_r2r(r5, r6);
+    movq_r2r(r0, r5);
+    movq_r2m(r7, *(output_data + 60));
+
+    psrlq_i2r(16, r5);
+    pand_m2r(*M(2), r5);
+    movq_r2r(r0, r7);
+    por_r2r(r5, r6);
+    pand_r2r(r2, r0);
+    pxor_r2r(r0, r7);
+    psllq_i2r(32, r0);
+    movq_r2m(r6, *(output_data + 52));
+
+    psrlq_i2r(16, r4);
+    movq_m2r(*(input_data + 36), r5);
+    psllq_i2r(16, r7);
+    pmullw_m2r(*(dequant_matrix + 36), r5);
+    movq_r2r(r7, r6);
+    movq_m2r(*M(2), r3);
+    psllq_i2r(16, r6);
+    pand_m2r(*M(3), r7);
+    pand_r2r(r1, r3);
+    por_r2r(r0, r7);
+    movq_r2r(r1, r0);
+    pand_m2r(*M(3), r1);
+    por_r2r(r3, r6);
+    movq_r2r(r4, r3);
+    psrlq_i2r(32, r1);
+    pand_r2r(r2, r3);
+    por_r2r(r1, r7);
+    por_r2r(r3, r7);
+    movq_r2r(r4, r3);
+    pand_m2r(*M(1), r3);
+    movq_r2r(r5, r1);
+    movq_r2m(r7, *(output_data + 44));
+
+    psrlq_i2r(48, r5);
+    movq_m2r(*(input_data + 32), r7);
+    por_r2r(r3, r6);
+    pmullw_m2r(*(dequant_matrix + 32), r7);
+    por_r2r(r5, r6);
+    pand_m2r(*M(2), r4);
+    psllq_i2r(32, r0);
+    movq_r2m(r6, *(output_data + 36));
+
+    movq_r2r(r0, r6);
+    pand_m2r(*M(3), r0);
+    psllq_i2r(16, r6);
+    movq_m2r(*(input_data + 20), r5);
+    movq_r2r(r1, r3);
+    pmullw_m2r(*(dequant_matrix + 40), r5);
+    psrlq_i2r(16, r1);
+    pand_m2r(*M(1), r1);
+    por_r2r(r4, r0);
+    pand_r2r(r7, r2);
+    por_r2r(r1, r0);
+    por_r2r(r2, r0);
+    psllq_i2r(16, r3);
+    movq_r2r(r3, r4);
+    movq_r2r(r5, r2);
+    movq_r2m(r0, *(output_data + 56));
+
+    psrlq_i2r(48, r2);
+    pand_m2r(*M(2), r4);
+    por_r2r(r2, r6);
+    movq_m2r(*M(1), r2);
+    por_r2r(r4, r6);
+    pand_r2r(r7, r2);
+    psllq_i2r(32, r3);
+    por_m2r(*(output_data + 40), r3);
+
+    por_r2r(r2, r6);
+    movq_m2r(*M(3), r2);
+    psllq_i2r(16, r5);
+    movq_r2m(r6, *(output_data + 48));
+
+    pand_r2r(r5, r2);
+    movq_m2r(*M(2), r6);
+    pxor_r2r(r2, r5);
+    pand_r2r(r7, r6);
+    psrlq_i2r(32, r2);
+    pand_m2r(*M(3), r7);
+    por_r2r(r2, r3);
+    por_m2r(*(output_data + 32), r7);
+
+    por_r2r(r3, r6);
+    por_r2r(r5, r7);
+    movq_r2m(r6, *(output_data + 40));
+    movq_r2m(r7, *(output_data + 32));
+
+
+#undef M
+
+    /* at this point, function has completed dequantization + dezigzag + 
+     * partial transposition; now do the idct itself */
+
+#define I(K) (output_data + K * 8)
+#define J(K) (output_data + ((K - 4) * 8) + 4)
+
+    RowIDCT();
+    Transpose();
+
+#undef I
+#undef J
+#define I(K) (output_data + (K * 8) + 32)
+#define J(K) (output_data + ((K - 4) * 8) + 36)
+
+    RowIDCT();
+    Transpose();
+
+#undef I
+#undef J
+#define I(K) (output_data + K * 8)
+#define J(K) (output_data + K * 8)
+
+    ColumnIDCT();
+
+#undef I
+#undef J
+#define I(K) (output_data + (K * 8) + 4)
+#define J(K) (output_data + (K * 8) + 4)
+
+    ColumnIDCT();
+
+#undef I
+#undef J
+
+}
+
+void vp3_idct_put_mmx(int16_t *input_data, int16_t *dequant_matrix,
+    int coeff_count, uint8_t *dest, int stride)
+{
+    int16_t transformed_data[64];
+    int16_t *op;
+    int i, j;
+    uint8_t vector128[8] = { 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80 };
+
+    vp3_idct_mmx(input_data, dequant_matrix, transformed_data);
+
+    /* place in final output */
+    op = transformed_data;
+    movq_m2r(*vector128, mm0);
+    for (i = 0; i < 8; i++) {
+#if 1
+        for (j = 0; j < 8; j++) {
+            if (*op < -128)
+                *dest = 0;
+            else if (*op > 127)
+                *dest = 255;
+            else
+                *dest = (uint8_t)(*op + 128);
+            op++;
+            dest++;
+        }
+        dest += (stride - 8);
+#else
+/* prototype optimization */
+        pxor_r2r(mm1, mm1);
+        packsswb_m2r(*(op + 4), mm1);
+        movq_r2r(mm1, mm2);
+        psrlq_i2r(32, mm2);
+        packsswb_m2r(*(op + 0), mm1);
+        op += 8;
+        por_r2r(mm2, mm1);
+        paddb_r2r(mm0, mm1);
+        movq_r2m(mm1, *dest);
+        dest += stride;
+#endif
+    }
+
+    /* be a good MMX citizen */
+    emms();
+}
+
+void vp3_idct_add_mmx(int16_t *input_data, int16_t *dequant_matrix,
+    int coeff_count, uint8_t *dest, int stride)
+{
+    int16_t transformed_data[64];
+    int16_t *op;
+    int i, j;
+    int16_t sample;
+
+    vp3_idct_mmx(input_data, dequant_matrix, transformed_data);
+
+    /* place in final output */
+    op = transformed_data;
+    for (i = 0; i < 8; i++) {
+        for (j = 0; j < 8; j++) {
+            sample = *dest + *op;
+            if (sample < 0)
+                *dest = 0;
+            else if (sample > 255)
+                *dest = 255;
+            else
+                *dest = (uint8_t)(sample & 0xFF);
+            op++;
+            dest++;
+        }
+        dest += (stride - 8);
+    }
+
+    /* be a good MMX citizen */
+    emms();
+}