unroll byteSwap() loop for common case

diff --git a/src/libFLAC/md5.c b/src/libFLAC/md5.c
index db1a65f..47e163f 100644 (file)
--- a/src/libFLAC/md5.c
+++ b/src/libFLAC/md5.c
@@ -138,16 +138,39 @@ static void FLAC__MD5Transform(FLAC__uint32 buf[4], FLAC__uint32 const in[16])
 
 #if WORDS_BIGENDIAN
 //@@@@@@ OPT: use bswap/intrinsics
-FLaC__INLINE static void byteSwap(FLAC__uint32 *buf, unsigned words)
+static void byteSwap(FLAC__uint32 *buf, unsigned words)
 {
+       register FLAC__uint32 x;
        do {
-               FLAC__byte *p = (FLAC__byte *)buf;
-               *buf++ = (FLAC__uint32)((unsigned)p[3] << 8 | p[2]) << 16 | ((unsigned)p[1] << 8 | p[0]);
-               p += 4;
+               x = *buf; 
+               x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff);
+               *buf++ = (x >> 16) | (x << 16);
        } while (--words);
 }
+static void byteSwapX16(FLAC__uint32 *buf)
+{
+       register FLAC__uint32 x;
+
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf++ = (x >> 16) | (x << 16);
+       x = *buf; x = ((x << 8) & 0xff00ff00) | ((x >> 8) & 0x00ff00ff); *buf   = (x >> 16) | (x << 16);
+}
 #else
 #define byteSwap(buf, words)
+#define byteSwapX16(buf)
 #endif
 
 /*
@@ -171,7 +194,7 @@ static void FLAC__MD5Update(FLAC__MD5Context *ctx, FLAC__byte const *buf, unsign
        }
        /* First chunk is an odd size */
        memcpy((FLAC__byte *)ctx->in + 64 - t, buf, t);
-       byteSwap(ctx->in, 16);
+       byteSwapX16(ctx->in);
        FLAC__MD5Transform(ctx->buf, ctx->in);
        buf += t;
        len -= t;
@@ -179,7 +202,7 @@ static void FLAC__MD5Update(FLAC__MD5Context *ctx, FLAC__byte const *buf, unsign
        /* Process data in 64-byte chunks */
        while (len >= 64) {
                memcpy(ctx->in, buf, 64);
-               byteSwap(ctx->in, 16);
+               byteSwapX16(ctx->in);
                FLAC__MD5Transform(ctx->buf, ctx->in);
                buf += 64;
                len -= 64;
@@ -224,7 +247,7 @@ void FLAC__MD5Final(FLAC__byte digest[16], FLAC__MD5Context *ctx)
 
        if (count < 0) {        /* Padding forces an extra block */
                memset(p, 0, count + 8);
-               byteSwap(ctx->in, 16);
+               byteSwapX16(ctx->in);
                FLAC__MD5Transform(ctx->buf, ctx->in);
                p = (FLAC__byte *)ctx->in;
                count = 56;