source/rcdaq/simpleRandom.cc

0001 #include "simpleRandom.h"
0002 #include <math.h>
0003 #include <strings.h>
0004
0005
0006
0007 /*
0008  * Shuffle the bytes into little-endian order within words, as per the
0009  * MD5 spec.  Note: this code works regardless of the byte order.
0010  */
0011 void
0012 simpleRandom::byteSwap(word32 *buf, unsigned words)
0013 {
0014         byte *p = (byte *)buf;
0015
0016         do {
0017                 *buf++ = (word32)((unsigned)p[3] << 8 | p[2]) << 16 |
0018                         ((unsigned)p[1] << 8 | p[0]);
0019                 p += 4;
0020         } while (--words);
0021 }
0022
0023 /*
0024  * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
0025  * initialization constants.
0026  */
0027 void
0028 simpleRandom::xMD5Init(struct xMD5Context *ctx)
0029 {
0030         ctx->buf[0] = 0x67452301;
0031         ctx->buf[1] = 0xefcdab89;
0032         ctx->buf[2] = 0x98badcfe;
0033         ctx->buf[3] = 0x10325476;
0034
0035         ctx->bytes[0] = 0;
0036         ctx->bytes[1] = 0;
0037 }
0038
0039 /*
0040  * Update context to reflect the concatenation of another buffer full
0041  * of bytes.
0042  */
0043 void
0044 simpleRandom::xMD5Update(struct xMD5Context *ctx, byte const *buf, int len)
0045 {
0046         word32 t;
0047
0048         /* Update byte count */
0049
0050         t = ctx->bytes[0];
0051         if ((ctx->bytes[0] = t + len) < t)
0052                 ctx->bytes[1]++;        /* Carry from low to high */
0053
0054         t = 64 - (t & 0x3f);    /* Space available in ctx->in (at least 1) */
0055         if (t > len) {
0056                 bcopy(buf, (byte *)ctx->in + 64 - (unsigned)t, len);
0057                 return;
0058         }
0059         /* First chunk is an odd size */
0060         bcopy(buf,(byte *)ctx->in + 64 - (unsigned)t, (unsigned)t);
0061         byteSwap(ctx->in, 16);
0062         xMD5Transform(ctx->buf, ctx->in);
0063         buf += (unsigned)t;
0064         len -= (unsigned)t;
0065
0066         /* Process data in 64-byte chunks */
0067         while (len >= 64) {
0068                 bcopy(buf, ctx->in, 64);
0069                 byteSwap(ctx->in, 16);
0070                 xMD5Transform(ctx->buf, ctx->in);
0071                 buf += 64;
0072                 len -= 64;
0073         }
0074
0075         /* Handle any remaining bytes of data. */
0076         bcopy(buf, ctx->in, len);
0077 }
0078
0079 /*
0080  * Final wrapup - pad to 64-byte boundary with the bit pattern
0081  * 1 0* (64-bit count of bits processed, MSB-first)
0082  */
0083 void
0084 simpleRandom::xMD5Final(byte bdigest[16], struct xMD5Context *ctx)
0085 {
0086         int count = (int)(ctx->bytes[0] & 0x3f); /* Bytes in ctx->in */
0087         byte *p = (byte *)ctx->in + count;      /* First unused byte */
0088
0089         /* Set the first char of padding to 0x80.  There is always room. */
0090         *p++ = 0x80;
0091
0092         /* Bytes of padding needed to make 56 bytes (-8..55) */
0093         count = 56 - 1 - count;
0094
0095         if (count < 0) {        /* Padding forces an extra block */
0096                 bzero(p, count+8);
0097                 byteSwap(ctx->in, 16);
0098                 xMD5Transform(ctx->buf, ctx->in);
0099                 p = (byte *)ctx->in;
0100                 count = 56;
0101         }
0102         bzero(p, count+8);
0103         byteSwap(ctx->in, 14);
0104
0105         /* Append length in bits and transform */
0106         ctx->in[14] = ctx->bytes[0] << 3;
0107         ctx->in[15] = ctx->bytes[1] << 3 | ctx->bytes[0] >> 29;
0108         xMD5Transform(ctx->buf, ctx->in);
0109
0110         byteSwap(ctx->buf, 4);
0111         bcopy(ctx->buf, bdigest, 16);
0112         bzero(ctx,sizeof(*ctx));
0113 }
0114
0115
0116 /* The four core functions - F1 is optimized somewhat */
0117
0118 /* #define F1(x, y, z) (x & y | ~x & z) */
0119 #define F1(x, y, z) (z ^ (x & (y ^ z)))
0120 #define F2(x, y, z) F1(z, x, y)
0121 #define F3(x, y, z) (x ^ y ^ z)
0122 #define F4(x, y, z) (y ^ (x | ~z))
0123
0124 /* This is the central step in the MD5 algorithm. */
0125 #define MD5STEP(f,w,x,y,z,in,s) \
0126          (w += f(x,y,z) + in, w = (w<<s | w>>(32-s)) + x)
0127
0128 /*
0129  * The core of the MD5 algorithm, this alters an existing MD5 hash to
0130  * reflect the addition of 16 longwords of new data.  MD5Update blocks
0131  * the data and converts bytes into longwords for this routine.
0132  */
0133 void
0134 simpleRandom::xMD5Transform(word32 buf[4], word32 const in[16])
0135 {
0136         word32 a, b, c, d;
0137
0138         a = buf[0];
0139         b = buf[1];
0140         c = buf[2];
0141         d = buf[3];
0142
0143         MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
0144         MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
0145         MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
0146         MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
0147         MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
0148         MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
0149         MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
0150         MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
0151         MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
0152         MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
0153         MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
0154         MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
0155         MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
0156         MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
0157         MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
0158         MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
0159
0160         MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
0161         MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
0162         MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
0163         MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
0164         MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
0165         MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
0166         MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
0167         MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
0168         MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
0169         MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
0170         MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
0171         MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
0172         MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
0173         MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
0174         MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
0175         MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
0176
0177         MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
0178         MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
0179         MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
0180         MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
0181         MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
0182         MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
0183         MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
0184         MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
0185         MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
0186         MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
0187         MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
0188         MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
0189         MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
0190         MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
0191         MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
0192         MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
0193
0194         MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
0195         MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
0196         MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
0197         MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
0198         MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
0199         MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
0200         MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
0201         MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
0202         MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
0203         MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
0204         MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
0205         MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
0206         MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
0207         MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
0208         MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
0209         MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
0210
0211         buf[0] += a;
0212         buf[1] += b;
0213         buf[2] += c;
0214         buf[3] += d;
0215 }
0216
0217
0218 void simpleRandom::MD5(byte *dest, const byte *orig, int len)
0219 {
0220         struct xMD5Context context;
0221
0222         xMD5Init(&context);
0223         xMD5Update(&context, orig, len);
0224         xMD5Final(dest, &context);
0225 }
0226
0227 /*****************************************************************/
0228
0229 simpleRandom::simpleRandom()
0230 {
0231   digest[0] = 7657635;
0232   digest[1] = 5565649;
0233   digest[2] = 9827729;
0234   digest[3] = 9892898;
0235
0236
0237 }
0238
0239 simpleRandom::simpleRandom( const int iseed)
0240 {
0241   digest[0] = iseed;
0242   digest[1] = 565649;
0243   digest[2] = 6827729;
0244   digest[3] = 2892898;
0245
0246 }
0247
0248 float simpleRandom::gauss(const float mean, const float sigma)
0249 {
0250 #define BIGNUMBER 100000
0251
0252   float y = 0.;
0253   while(y == 0.)
0254     {
0255       y = rnd(0,BIGNUMBER);
0256     }
0257   float z = rnd(0,BIGNUMBER);
0258
0259   y /= BIGNUMBER;
0260   z /= BIGNUMBER;
0261
0262   float x = z * 6.283185;
0263
0264 #if defined(SunOS) || defined(Linux)
0265   float result = mean + sigma* sin(x) * sqrt(-2 * log(y) );
0266 #else
0267   float result = mean + sigma* sinf(x) * sqrtf(-2 * logf(y) );
0268 #endif
0269
0270   return result;
0271 }
0272
0273 float simpleRandom::rnd(int low, int high)
0274 {
0275         unsigned int range = high - low;
0276         unsigned int mask = 0;
0277         unsigned int num;
0278         int r;
0279
0280         for (r = range; r; r >>= 1)
0281                 mask |= r;
0282
0283         do {
0284                 MD5((byte*)digest,(const byte *) digest, sizeof(digest));
0285                 num = digest[0] & mask;
0286         } while (num > range);
0287
0288         return num + low;
0289 }