2 * Copyright 1985, 1988 by the Massachusetts Institute of Technology.
4 * For copying and distribution information, please
5 * see the file <mit-cpyright.h>.
7 * This routine generates the P permutation code for the DES.
10 #include <afsconfig.h>
11 #include <afs/param.h>
15 #include <mit-cpyright.h>
18 #include "des_internal.h"
20 #include "des_prototypes.h"
22 void gen(FILE *stream)
24 /* P permutes 32 bit input R1 into 32 bit output R2 */
26 /* clear the output */
27 fprintf(stream," L2 = 0;\n");
29 fprintf(stream," R2 = 0;\n");
31 "/* P operations */\n/* from right to right */\n");
32 /* first list mapping from left to left */
33 for (i = 0; i <=31; i++)
36 " if (R1 & (1<<%d)) R2 |= 1<<%d;\n",P[i],i);
38 /* flip p into p_temp */
39 fprintf(stream," P_temp = R1;\n");
40 fprintf(stream," P_temp_p = (unsigned char *) &P_temp;\n");
43 fprintf(stream," R2 = P_prime[0][*P_temp_p++];\n");
44 fprintf(stream," R2 |= P_prime[1][*P_temp_p++];\n");
45 fprintf(stream," R2 |= P_prime[2][*P_temp_p++];\n");
46 fprintf(stream," R2 |= P_prime[3][*P_temp_p];\n");
48 fprintf(stream," R2 = P_prime[3][*P_temp_p++];\n");
49 fprintf(stream," R2 |= P_prime[2][*P_temp_p++];\n");
50 fprintf(stream," R2 |= P_prime[1][*P_temp_p++];\n");
51 fprintf(stream," R2 |= P_prime[0][*P_temp_p];\n");