mirrors/tiny-AES-c
1
0
Fork 0
mirror of https://github.com/kokke/tiny-AES-c synced 2024-11-22 05:21:52 +03:00
Code Issues Packages Projects Releases Wiki Activity

Commenting reason for extra calls to xtime()

Browse Source
This commit is contained in:
kokke 2018-05-02 15:23:47 +02:00 committed by GitHub
parent f4b1701a52
commit 03be0caa72
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 4 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
aes.c
View File

@ -319,6 +319,9 @@ static void MixColumns(state_t* state)
}
// Multiply is used to multiply numbers in the field GF(2^8)
// Note: The last call to xtime() is unneeded, but often ends up generating a smaller binary
// The compiler seems to be able to vectorize the operation better this way.
// See https://github.com/kokke/tiny-AES-c/pull/34
#if MULTIPLY_AS_A_FUNCTION
static uint8_t Multiply(uint8_t x, uint8_t y)
{
@ -326,7 +329,7 @@ static uint8_t Multiply(uint8_t x, uint8_t y)
((y>>1 & 1) * xtime(x)) ^
((y>>2 & 1) * xtime(xtime(x))) ^
((y>>3 & 1) * xtime(xtime(xtime(x)))) ^
((y>>4 & 1) * xtime(xtime(xtime(xtime(x))))));
((y>>4 & 1) * xtime(xtime(xtime(xtime(x)))))); /* this last call to xtime() can be omitted */
}
#else
#define Multiply(x, y) \