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Blowfish: restructure/simplify code a bit.

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Very slightly faster (2% or so)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-07-06 01:37:44 +02:00
parent 9862cbd7a4
commit ec08676232
1 changed files with 18 additions and 26 deletions
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44
libavutil/blowfish.c
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@ -294,24 +294,12 @@ static const uint32_t orig_s[4][256] = {
0xB74E6132, 0xCE77E25B, 0x578FDFE3, 0x3AC372E6 }
};
static void F(AVBlowfish *ctx, uint32_t *xl, uint32_t *xr, int i)
{
uint32_t Xl, Xr;
uint32_t y;
Xl = *xl;
Xr = *xr;
Xl ^= ctx->p[i];
y = ctx->s[0][(Xl >> 24) & 0xFF];
y += ctx->s[1][(Xl >> 16) & 0xFF];
y ^= ctx->s[2][(Xl >> 8) & 0xFF];
y += ctx->s[3][ Xl & 0xFF];
Xr ^= y;
*xl = Xr;
*xr = Xl;
}
#define F(Xl, Xr, P) \
Xr ^=((( ctx->s[0][ Xl >> 24 ] \
+ ctx->s[1][(Xl >> 16) & 0xFF])\
^ ctx->s[2][(Xl >> 8) & 0xFF])\
+ ctx->s[3][ Xl & 0xFF])\
^ P;
av_cold void av_blowfish_init(AVBlowfish *ctx, const uint8_t *key, int key_len)
{
@ -358,17 +346,21 @@ void av_blowfish_crypt_ecb(AVBlowfish *ctx, uint32_t *xl, uint32_t *xr,
Xr = *xr;
if (decrypt) {
for (i = AV_BF_ROUNDS + 1; i > 1; --i)
F(ctx, &Xl, &Xr, i);
Xl ^= ctx->p[AV_BF_ROUNDS + 1];
for (i = AV_BF_ROUNDS; i > 0; i-=2) {
F(Xl, Xr, ctx->p[i ]);
F(Xr, Xl, ctx->p[i-1]);
}
Xl = Xl ^ ctx->p[1];
Xr = Xr ^ ctx->p[0];
Xr ^= ctx->p[0];
} else {
for (i = 0; i < AV_BF_ROUNDS; ++i)
F(ctx, &Xl, &Xr, i);
Xl ^= ctx->p[0];
for (i = 1; i < AV_BF_ROUNDS+1; i+=2){
F(Xl, Xr, ctx->p[i ]);
F(Xr, Xl, ctx->p[i+1]);
}
Xl = Xl ^ ctx->p[AV_BF_ROUNDS];
Xr = Xr ^ ctx->p[AV_BF_ROUNDS + 1];
Xr ^= ctx->p[AV_BF_ROUNDS + 1];
}
*xl = Xr;