Move Alpha optimized IDCT to own file. Based on a patch by MÃ¥ns

Rullgård <mru@users.sourceforge.net>.

I've left out the idctCol2 part, because W4 has recently been decreed
to be 16383, and also I doubt it will give a noticeable speedup.

Originally committed as revision 1029 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 306 insertions, 0 deletions

diff --git a/libavcodec/alpha/simple_idct_alpha.c b/libavcodec/alpha/simple_idct_alpha.c
new file mode 100644
index 0000000000..31677184e0
--- /dev/null
+++ b/libavcodec/alpha/simple_idct_alpha.c
@@ -0,0 +1,306 @@
+/*
+ * Simple IDCT (Alpha optimized)
+ *
+ * Copyright (c) 2001 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * 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
+ *
+ * based upon some outcommented c code from mpeg2dec (idct_mmx.c
+ * written by Aaron Holtzman <aholtzma@ess.engr.uvic.ca>)
+ *
+ * Alpha optimiziations by Måns Rullgård <mru@users.sourceforge.net>
+ *                     and Falk Hueffner <falk@debian.org>
+ */
+
+#include "asm.h"
+#include "../dsputil.h"
+
+// cos(i * M_PI / 16) * sqrt(2) * (1 << 14)
+// W4 is actually exactly 16384, but using 16383 works around
+// accumulating rounding errors for some encoders
+#define W1 ((int_fast32_t) 22725)
+#define W2 ((int_fast32_t) 21407)
+#define W3 ((int_fast32_t) 19266)
+#define W4 ((int_fast32_t) 16383)
+#define W5 ((int_fast32_t) 12873)
+#define W6 ((int_fast32_t)  8867)
+#define W7 ((int_fast32_t)  4520)
+#define ROW_SHIFT 11
+#define COL_SHIFT 20
+
+/* 0: all entries 0, 1: only first entry nonzero, 2: otherwise  */
+static inline int idct_row(DCTELEM *row)
+{
+    int_fast32_t a0, a1, a2, a3, b0, b1, b2, b3, t;
+    uint64_t l, r;
+    l = ldq(row);
+    r = ldq(row + 4);
+
+    if (l == 0 && r == 0)
+        return 0;
+    
+    a0 = W4 * sextw(l) + (1 << (ROW_SHIFT - 1));
+
+    if (((l & ~0xffffUL) | r) == 0) {
+        a0 >>= ROW_SHIFT;
+        a0 = (uint16_t) a0;
+        a0 |= a0 << 16;
+        a0 |= a0 << 32;
+        
+        stq(a0, row);
+        stq(a0, row + 4);
+        return 1;
+    }
+
+    a1 = a0;
+    a2 = a0;
+    a3 = a0;
+
+    t = extwl(l, 4);            /* row[2] */
+    if (t != 0) {
+        t = sextw(t);
+        a0 += W2 * t;
+        a1 += W6 * t;
+        a2 -= W6 * t;
+        a3 -= W2 * t;
+    }
+
+    t = extwl(r, 0);            /* row[4] */
+    if (t != 0) {
+        t = sextw(t);
+        a0 += W4 * t;
+        a1 -= W4 * t;
+        a2 -= W4 * t;
+        a3 += W4 * t;
+    }
+
+    t = extwl(r, 4);            /* row[6] */
+    if (t != 0) {
+        t = sextw(t);
+        a0 += W6 * t;
+        a1 -= W2 * t;
+        a2 += W2 * t;
+        a3 -= W6 * t;
+    }
+
+    t = extwl(l, 2);            /* row[1] */
+    if (t != 0) {
+        t = sextw(t);
+        b0 = W1 * t;
+        b1 = W3 * t;
+        b2 = W5 * t;
+        b3 = W7 * t;
+    } else {
+        b0 = 0;
+        b1 = 0;
+        b2 = 0;
+        b3 = 0;
+    }
+
+    t = extwl(l, 6);            /* row[3] */
+    if (t) {
+        t = sextw(t);
+        b0 += W3 * t;
+        b1 -= W7 * t;
+        b2 -= W1 * t;
+        b3 -= W5 * t;
+    }
+
+    
+    t = extwl(r, 2);            /* row[5] */
+    if (t) {
+        t = sextw(t);
+        b0 += W5 * t;
+        b1 -= W1 * t;
+        b2 += W7 * t;
+        b3 += W3 * t;
+    }
+
+    t = extwl(r, 6);            /* row[7] */
+    if (t) {
+        t = sextw(t);
+        b0 += W7 * t;
+        b1 -= W5 * t;
+        b2 += W3 * t;
+        b3 -= W1 * t;
+    }
+
+    row[0] = (a0 + b0) >> ROW_SHIFT;
+    row[1] = (a1 + b1) >> ROW_SHIFT;
+    row[2] = (a2 + b2) >> ROW_SHIFT;
+    row[3] = (a3 + b3) >> ROW_SHIFT;
+    row[4] = (a3 - b3) >> ROW_SHIFT;
+    row[5] = (a2 - b2) >> ROW_SHIFT;
+    row[6] = (a1 - b1) >> ROW_SHIFT;
+    row[7] = (a0 - b0) >> ROW_SHIFT;
+
+    return 2;
+}
+
+static inline void idct_col(DCTELEM *col)
+{
+    int_fast32_t a0, a1, a2, a3, b0, b1, b2, b3;
+
+    col[0] += (1 << (COL_SHIFT - 1)) / W4;
+
+    a0 = W4 * col[8 * 0];
+    a1 = W4 * col[8 * 0];
+    a2 = W4 * col[8 * 0];
+    a3 = W4 * col[8 * 0];
+
+    if (col[8 * 2]) {
+        a0 += W2 * col[8 * 2];
+        a1 += W6 * col[8 * 2];
+        a2 -= W6 * col[8 * 2];
+        a3 -= W2 * col[8 * 2];
+    }
+
+    if (col[8 * 4]) {
+        a0 += W4 * col[8 * 4];
+        a1 -= W4 * col[8 * 4];
+        a2 -= W4 * col[8 * 4];
+        a3 += W4 * col[8 * 4];
+    }
+
+    if (col[8 * 6]) {
+        a0 += W6 * col[8 * 6];
+        a1 -= W2 * col[8 * 6];
+        a2 += W2 * col[8 * 6];
+        a3 -= W6 * col[8 * 6];
+    }
+
+    if (col[8 * 1]) {
+        b0 = W1 * col[8 * 1];
+        b1 = W3 * col[8 * 1];
+        b2 = W5 * col[8 * 1];
+        b3 = W7 * col[8 * 1];
+    } else {
+        b0 = 0;
+        b1 = 0;
+        b2 = 0;
+        b3 = 0;
+    }
+
+    if (col[8 * 3]) {
+        b0 += W3 * col[8 * 3];
+        b1 -= W7 * col[8 * 3];
+        b2 -= W1 * col[8 * 3];
+        b3 -= W5 * col[8 * 3];
+    }
+
+    if (col[8 * 5]) {
+        b0 += W5 * col[8 * 5];
+        b1 -= W1 * col[8 * 5];
+        b2 += W7 * col[8 * 5];
+        b3 += W3 * col[8 * 5];
+    }
+
+    if (col[8 * 7]) {
+        b0 += W7 * col[8 * 7];
+        b1 -= W5 * col[8 * 7];
+        b2 += W3 * col[8 * 7];
+        b3 -= W1 * col[8 * 7];
+    }
+
+    col[8 * 0] = (a0 + b0) >> COL_SHIFT;
+    col[8 * 7] = (a0 - b0) >> COL_SHIFT;
+    col[8 * 1] = (a1 + b1) >> COL_SHIFT;
+    col[8 * 6] = (a1 - b1) >> COL_SHIFT;
+    col[8 * 2] = (a2 + b2) >> COL_SHIFT;
+    col[8 * 5] = (a2 - b2) >> COL_SHIFT;
+    col[8 * 3] = (a3 + b3) >> COL_SHIFT;
+    col[8 * 4] = (a3 - b3) >> COL_SHIFT;
+}
+
+/* If all rows but the first one are zero after row transformation,
+   all rows will be identical after column transformation.  */
+static inline void idct_col2(DCTELEM *col)
+{
+    int i;
+    uint64_t l, r;
+    uint64_t *lcol = (uint64_t *) col;
+
+    for (i = 0; i < 8; ++i) {
+        int_fast32_t a0 = col[0] + (1 << (COL_SHIFT - 1)) / W4;
+
+        a0 *= W4;
+        col[0] = a0 >> COL_SHIFT;
+        ++col;
+    }
+
+    l = lcol[0];
+    r = lcol[1];
+    lcol[ 2] = l; lcol[ 3] = r;
+    lcol[ 4] = l; lcol[ 5] = r;
+    lcol[ 6] = l; lcol[ 7] = r;
+    lcol[ 8] = l; lcol[ 9] = r;
+    lcol[10] = l; lcol[11] = r;
+    lcol[12] = l; lcol[13] = r;
+    lcol[14] = l; lcol[15] = r;
+}
+
+void simple_idct_axp(DCTELEM *block)
+{
+
+    int i;
+    int rowsZero = 1;           /* all rows except row 0 zero */
+    int rowsConstant = 1;       /* all rows consist of a constant value */
+
+    for (i = 0; i < 8; i++) {
+        int sparseness = idct_row(block + 8 * i);
+
+        if (i > 0 && sparseness > 0)
+            rowsZero = 0;
+        if (sparseness == 2)
+            rowsConstant = 0;
+    }
+
+    if (rowsZero) {
+        idct_col2(block);
+    } else if (rowsConstant) {
+        uint64_t *lblock = (uint64_t *) block;
+
+        idct_col(block);
+        for (i = 0; i < 8; i += 2) {
+            uint64_t v = (uint16_t) block[i * 8];
+            uint64_t w = (uint16_t) block[i * 8 + 8];
+
+            v |= v << 16;
+            w |= w << 16;
+            v |= v << 32;
+            w |= w << 32;
+            lblock[0] = v;
+            lblock[1] = v;
+            lblock[2] = w;
+            lblock[3] = w;
+            lblock += 4;
+        }
+    } else {
+        for (i = 0; i < 8; i++)
+            idct_col(block + i);
+    }
+}
+
+void simple_idct_put_axp(uint8_t *dest, int line_size, DCTELEM *block)
+{
+    simple_idct_axp(block);
+    put_pixels_clamped(block, dest, line_size);
+}
+
+void simple_idct_add_axp(uint8_t *dest, int line_size, DCTELEM *block)
+{
+    simple_idct_axp(block);
+    add_pixels_clamped(block, dest, line_size);
+}