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xts128.c: minor optimizaton.

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This commit is contained in:
Andy Polyakov 2011-05-04 20:57:43 +00:00
parent c9adde0699
commit c7d0d0ae09
1 changed files with 14 additions and 12 deletions
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26
crypto/modes/xts128.c
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@ -107,14 +107,15 @@ int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, const unsigned char iv[16],
tweak.u[1] = (tweak.u[1]<<1)|carry;
}
else {
unsigned int carry,c;
size_t c;
for (carry=0,i=0;i<16;++i) {
c = tweak.c[i];
tweak.c[i] = (c<<1)|carry;
carry = c>>7;
for (c=0,i=0;i<16;++i) {
/*+ substitutes for |, because c is 1 bit */
c += ((size_t)tweak.c[i])<<1;
tweak.c[i] = (u8)c;
c = c>>8;
}
tweak.c[0] ^= 0x87&(0-carry);
tweak.c[0] ^= (u8)(0x87&(0-c));
}
}
if (enc) {
@ -142,14 +143,15 @@ int CRYPTO_xts128_encrypt(const XTS128_CONTEXT *ctx, const unsigned char iv[16],
tweak1.u[1] = (tweak.u[1]<<1)|carry;
}
else {
unsigned int carry,c;
size_t c;
for (carry=0,i=0;i<16;++i) {
c = tweak.c[i];
tweak1.c[i] = (c<<1)|carry;
carry = c>>7;
for (c=0,i=0;i<16;++i) {
/*+ substitutes for |, because c is 1 bit */
c += ((size_t)tweak.c[i])<<1;
tweak1.c[i] = (u8)c;
c = c>>8;
}
tweak1.c[0] ^= 0x87&(0-carry);
tweak1.c[0] ^= (u8)(0x87&(0-c));
}
#if defined(STRICT_ALIGNMENT)
memcpy(scratch.c,inp,16);