ref: 5e010fd8a82ec3b6552b4002bcd4be0586081e9a
dir: /sys/src/libsec/port/chachablock.c/
#include "os.h" #define ROTATE(v,c) ((u32int)((v) << (c)) | ((v) >> (32 - (c)))) #define QUARTERROUND(ia,ib,ic,id) { \ u32int a, b, c, d, t; \ a = x[ia]; b = x[ib]; c = x[ic]; d = x[id]; \ a += b; t = d^a; d = ROTATE(t,16); \ c += d; t = b^c; b = ROTATE(t,12); \ a += b; t = d^a; d = ROTATE(t, 8); \ c += d; t = b^c; b = ROTATE(t, 7); \ x[ia] = a; x[ib] = b; x[ic] = c; x[id] = d; \ } void _chachablock(u32int x[16], int rounds) { for(; rounds > 0; rounds -= 2) { QUARTERROUND(0, 4, 8,12) QUARTERROUND(1, 5, 9,13) QUARTERROUND(2, 6,10,14) QUARTERROUND(3, 7,11,15) QUARTERROUND(0, 5,10,15) QUARTERROUND(1, 6,11,12) QUARTERROUND(2, 7, 8,13) QUARTERROUND(3, 4, 9,14) } }