/* 
 * Copyright Ó 1992 by Xerox Corporation.  All rights reserved.
 * Carl Hauser, February 7, 1992
 * A straightforward implementation of the inner 16-word computation
 * of the proposed Secure Hash Standard (SHS), dated 22 January 1992
 * This function is applied to successive 16 word blocks of the final
 * padded message.  (The padding has to be done separately-- see section 4
 * of the SHS standard)
 *
 * To use: initialize a five word array, h, to 
 * {0x67452301, 0x0efcdab89, 0x98badcfe, 0x10325476, 0x0c3d2e1f0} 
 * and then pass h and pointers to successive 16 word message blocks 
 * to parameters h and m of onem.  
 * The five word hash is the contents of h after the last block 
 * has been processed. 
 */

#define S5(x) (((x)<<5) | ((x)>>27))
#define S30(x) (((x)<<30) | ((x)>>2))
#define K0 0x5a827999
#define K1 0x6ed9eba1
#define K2 0x8f1bbcdc
#define K3 0x0ca62c1d6
#define AND(x,y) ((x)&(y))
#define F0(x,y,z) (AND(x,y) | AND(~(x),z))
#define F1(x,y,z) ((x)^(y)^(z))
#define F2(x,y,z) (AND(x,y) | AND(x,z) | AND(y,z))
#define word unsigned long
static reversebytes(w)
word *w;
{
    char *p = (char *) w;
    char t;
    t = *p;
    *p = *(p+3);
    *(p+3) = t;
    t = *(p+1);
    *(p+1) = *(p+2);
    *(p+2) = t;
}

void onem(m, h)
word m[16];
word h[5];
{
    word w[80];
    int t;
    word A, B, C, D, E;
    word *p, *q;
    word *pm3, *pm8, *pm14, *pm16;
    word temp;
    int i;
#ifdef LITTLE_ENDIAN
    for (i=0; i<16; i++) {
       reversebytes(&(m[i));
    };
#endif
    A = h[0]; B=h[1]; C=h[2]; D=h[3]; E=h[4];
    for (p = m, q=w; p < m+16; p++, q++) {
        *q = *p;
        }
    pm3 = w+13; pm8 = w+8; pm14=w+2; pm16=w;
    for (p=w+16; p < w+80; p++, pm3++, pm8++, pm14++, pm16++) {
        *p = *pm3 ^ *pm8 ^ *pm14 ^ *pm16;
        }
    for (i=0; i<20; i++) {
        temp = S5(A) + F0(B,C,D) + E + w[i] + K0;
        E=D; D=C; C=S30(B); B=A; A=temp;
        }
    for (i=20; i<40; i++) {
        temp = S5(A) + F1(B,C,D) + E + w[i] + K1;
        E=D; D=C; C=S30(B); B=A; A=temp;
        }
    for (i=40; i<60; i++) {
        temp = S5(A) + F2(B,C,D) + E + w[i] + K2;
        E=D; D=C; C=S30(B); B=A; A=temp;
        }
    for (i=60; i<80; i++) {
        temp = S5(A) + F1(B,C,D) + E + w[i] + K3;
        E=D; D=C; C=S30(B); B=A; A=temp;
        }
    h[0]=h[0]+A;
    h[1]=h[1]+B;
    h[2]=h[2]+C;
    h[3]=h[3]+D;
    h[4]=h[4]+E;
    }