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/*
 * sha2_256 block cipher
 *
 * Implementation straight from Federal Information Processing Standards
 * publication 180-2 (+Change Notice to include SHA-224) August 1, 2002
 *   note: the following upper and lower case macro names are distinct
 *         and reflect the functions defined in FIPS pub. 180-2.
 */

#include <u.h>
#include <libc.h>

#define ROTR(x,n)       (((x) >> (n)) | ((x) << (32-(n))))
#define sigma0(x)       (ROTR((x),7) ^ ROTR((x),18) ^ ((x) >> 3))
#define sigma1(x)       (ROTR((x),17) ^ ROTR((x),19) ^ ((x) >> 10))
#define SIGMA0(x)       (ROTR((x),2) ^ ROTR((x),13) ^ ROTR((x),22))
#define SIGMA1(x)       (ROTR((x),6) ^ ROTR((x),11) ^ ROTR((x),25))
#define Ch(x,y,z)       (((x) & (y)) ^ ((~(x)) & (z)))
#define Maj(x,y,z)      (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))

/*
 * first 32 bits of the fractional parts of cube roots of
 * first 64 primes (2..311).
 */
static u32int K256[64] = {
        0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,
        0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
        0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,
        0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,
        0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,
        0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,
        0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,
        0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,
        0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,
        0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,
        0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,
        0xd192e819,0xd6990624,0xf40e3585,0x106aa070,
        0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,
        0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,
        0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,
        0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2,
};

void
_sha2block64(uchar *p, ulong len, u32int *s)
{
        u32int a, b, c, d, e, f, g, h, t1, t2;
        u32int *kp, *wp;
        u32int w[64];
        uchar *end;

        /* at this point, we have a multiple of 64 bytes */
        for(end = p+len; p < end;){
                a = s[0];
                b = s[1];
                c = s[2];
                d = s[3];
                e = s[4];
                f = s[5];
                g = s[6];
                h = s[7];

                for(wp = w; wp < &w[16]; wp++, p += 4)
                        wp[0] = p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3];
                for(; wp < &w[64]; wp++)
                        wp[0] = sigma1(wp[-2]) + wp[-7] +
                                sigma0(wp[-15]) + wp[-16];

                for(kp = K256, wp = w; wp < &w[64]; ) {
                        t1 = h + SIGMA1(e) + Ch(e,f,g) + *kp++ + *wp++;
                        t2 = SIGMA0(a) + Maj(a,b,c);
                        h = g;
                        g = f;
                        f = e;
                        e = d + t1;
                        d = c;
                        c = b;
                        b = a;
                        a = t1 + t2;
                }

                /* save state */
                s[0] += a;
                s[1] += b;
                s[2] += c;
                s[3] += d;
                s[4] += e;
                s[5] += f;
                s[6] += g;
                s[7] += h;
        }
}