Sanitize altivec code so it can be built with runtime check properly

Originally committed as revision 10640 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 153 insertions, 0 deletions

diff --git a/libavcodec/ppc/imgresample_altivec.c b/libavcodec/ppc/imgresample_altivec.c
new file mode 100644
index 0000000000..3b161c5a6d
--- /dev/null
+++ b/libavcodec/ppc/imgresample_altivec.c
@@ -0,0 +1,153 @@
+/*
+ * High quality image resampling with polyphase filters
+ * Copyright (c) 2001 Fabrice Bellard.
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file imgresample_altivec.c
+ * High quality image resampling with polyphase filters - AltiVec bits
+ */
+
+#include "gcc_fixes.h"
+
+typedef         union {
+    vector unsigned char v;
+    unsigned char c[16];
+} vec_uc_t;
+
+typedef         union {
+    vector signed short v;
+    signed short s[8];
+} vec_ss_t;
+
+void v_resample16_altivec(uint8_t *dst, int dst_width, const uint8_t *src,
+                          int wrap, int16_t *filter)
+{
+    int sum, i;
+    const uint8_t *s;
+    vector unsigned char *tv, tmp, dstv, zero;
+    vec_ss_t srchv[4], srclv[4], fv[4];
+    vector signed short zeros, sumhv, sumlv;
+    s = src;
+
+    for(i=0;i<4;i++)
+    {
+        /*
+           The vec_madds later on does an implicit >>15 on the result.
+           Since FILTER_BITS is 8, and we have 15 bits of magnitude in
+           a signed short, we have just enough bits to pre-shift our
+           filter constants <<7 to compensate for vec_madds.
+        */
+        fv[i].s[0] = filter[i] << (15-FILTER_BITS);
+        fv[i].v = vec_splat(fv[i].v, 0);
+    }
+
+    zero = vec_splat_u8(0);
+    zeros = vec_splat_s16(0);
+
+
+    /*
+       When we're resampling, we'd ideally like both our input buffers,
+       and output buffers to be 16-byte aligned, so we can do both aligned
+       reads and writes. Sadly we can't always have this at the moment, so
+       we opt for aligned writes, as unaligned writes have a huge overhead.
+       To do this, do enough scalar resamples to get dst 16-byte aligned.
+    */
+    i = (-(int)dst) & 0xf;
+    while(i>0) {
+        sum = s[0 * wrap] * filter[0] +
+        s[1 * wrap] * filter[1] +
+        s[2 * wrap] * filter[2] +
+        s[3 * wrap] * filter[3];
+        sum = sum >> FILTER_BITS;
+        if (sum<0) sum = 0; else if (sum>255) sum=255;
+        dst[0] = sum;
+        dst++;
+        s++;
+        dst_width--;
+        i--;
+    }
+
+    /* Do our altivec resampling on 16 pixels at once. */
+    while(dst_width>=16) {
+        /*
+           Read 16 (potentially unaligned) bytes from each of
+           4 lines into 4 vectors, and split them into shorts.
+           Interleave the multipy/accumulate for the resample
+           filter with the loads to hide the 3 cycle latency
+           the vec_madds have.
+        */
+        tv = (vector unsigned char *) &s[0 * wrap];
+        tmp = vec_perm(tv[0], tv[1], vec_lvsl(0, &s[i * wrap]));
+        srchv[0].v = (vector signed short) vec_mergeh(zero, tmp);
+        srclv[0].v = (vector signed short) vec_mergel(zero, tmp);
+        sumhv = vec_madds(srchv[0].v, fv[0].v, zeros);
+        sumlv = vec_madds(srclv[0].v, fv[0].v, zeros);
+
+        tv = (vector unsigned char *) &s[1 * wrap];
+        tmp = vec_perm(tv[0], tv[1], vec_lvsl(0, &s[1 * wrap]));
+        srchv[1].v = (vector signed short) vec_mergeh(zero, tmp);
+        srclv[1].v = (vector signed short) vec_mergel(zero, tmp);
+        sumhv = vec_madds(srchv[1].v, fv[1].v, sumhv);
+        sumlv = vec_madds(srclv[1].v, fv[1].v, sumlv);
+
+        tv = (vector unsigned char *) &s[2 * wrap];
+        tmp = vec_perm(tv[0], tv[1], vec_lvsl(0, &s[2 * wrap]));
+        srchv[2].v = (vector signed short) vec_mergeh(zero, tmp);
+        srclv[2].v = (vector signed short) vec_mergel(zero, tmp);
+        sumhv = vec_madds(srchv[2].v, fv[2].v, sumhv);
+        sumlv = vec_madds(srclv[2].v, fv[2].v, sumlv);
+
+        tv = (vector unsigned char *) &s[3 * wrap];
+        tmp = vec_perm(tv[0], tv[1], vec_lvsl(0, &s[3 * wrap]));
+        srchv[3].v = (vector signed short) vec_mergeh(zero, tmp);
+        srclv[3].v = (vector signed short) vec_mergel(zero, tmp);
+        sumhv = vec_madds(srchv[3].v, fv[3].v, sumhv);
+        sumlv = vec_madds(srclv[3].v, fv[3].v, sumlv);
+
+        /*
+           Pack the results into our destination vector,
+           and do an aligned write of that back to memory.
+        */
+        dstv = vec_packsu(sumhv, sumlv) ;
+        vec_st(dstv, 0, (vector unsigned char *) dst);
+
+        dst+=16;
+        s+=16;
+        dst_width-=16;
+    }
+
+    /*
+       If there are any leftover pixels, resample them
+       with the slow scalar method.
+    */
+    while(dst_width>0) {
+        sum = s[0 * wrap] * filter[0] +
+        s[1 * wrap] * filter[1] +
+        s[2 * wrap] * filter[2] +
+        s[3 * wrap] * filter[3];
+        sum = sum >> FILTER_BITS;
+        if (sum<0) sum = 0; else if (sum>255) sum=255;
+        dst[0] = sum;
+        dst++;
+        s++;
+        dst_width--;
+    }
+}
+