summaryrefslogtreecommitdiff
path: root/apps/plugins/puzzles/random.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--apps/plugins/puzzles/random.c350
1 files changed, 350 insertions, 0 deletions
diff --git a/apps/plugins/puzzles/random.c b/apps/plugins/puzzles/random.c
new file mode 100644
index 0000000..c129a8d
--- /dev/null
+++ b/apps/plugins/puzzles/random.c
@@ -0,0 +1,350 @@
+/*
+ * random.c: Internal random number generator, guaranteed to work
+ * the same way on all platforms. Used when generating an initial
+ * game state from a random game seed; required to ensure that game
+ * seeds can be exchanged between versions of a puzzle compiled for
+ * different platforms.
+ *
+ * The generator is based on SHA-1. This is almost certainly
+ * overkill, but I had the SHA-1 code kicking around and it was
+ * easier to reuse it than to do anything else!
+ */
+
+#include <string.h>
+#include <stdio.h>
+
+#include "puzzles.h"
+
+/* ----------------------------------------------------------------------
+ * Core SHA algorithm: processes 16-word blocks into a message digest.
+ */
+
+#define rol(x,y) ( ((x) << (y)) | (((uint32)x) >> (32-y)) )
+
+static void SHA_Core_Init(uint32 h[5])
+{
+ h[0] = 0x67452301;
+ h[1] = 0xefcdab89;
+ h[2] = 0x98badcfe;
+ h[3] = 0x10325476;
+ h[4] = 0xc3d2e1f0;
+}
+
+static void SHATransform(uint32 * digest, uint32 * block)
+{
+ uint32 w[80];
+ uint32 a, b, c, d, e;
+ int t;
+
+ for (t = 0; t < 16; t++)
+ w[t] = block[t];
+
+ for (t = 16; t < 80; t++) {
+ uint32 tmp = w[t - 3] ^ w[t - 8] ^ w[t - 14] ^ w[t - 16];
+ w[t] = rol(tmp, 1);
+ }
+
+ a = digest[0];
+ b = digest[1];
+ c = digest[2];
+ d = digest[3];
+ e = digest[4];
+
+ for (t = 0; t < 20; t++) {
+ uint32 tmp =
+ rol(a, 5) + ((b & c) | (d & ~b)) + e + w[t] + 0x5a827999;
+ e = d;
+ d = c;
+ c = rol(b, 30);
+ b = a;
+ a = tmp;
+ }
+ for (t = 20; t < 40; t++) {
+ uint32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0x6ed9eba1;
+ e = d;
+ d = c;
+ c = rol(b, 30);
+ b = a;
+ a = tmp;
+ }
+ for (t = 40; t < 60; t++) {
+ uint32 tmp = rol(a,
+ 5) + ((b & c) | (b & d) | (c & d)) + e + w[t] +
+ 0x8f1bbcdc;
+ e = d;
+ d = c;
+ c = rol(b, 30);
+ b = a;
+ a = tmp;
+ }
+ for (t = 60; t < 80; t++) {
+ uint32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0xca62c1d6;
+ e = d;
+ d = c;
+ c = rol(b, 30);
+ b = a;
+ a = tmp;
+ }
+
+ digest[0] += a;
+ digest[1] += b;
+ digest[2] += c;
+ digest[3] += d;
+ digest[4] += e;
+}
+
+/* ----------------------------------------------------------------------
+ * Outer SHA algorithm: take an arbitrary length byte string,
+ * convert it into 16-word blocks with the prescribed padding at
+ * the end, and pass those blocks to the core SHA algorithm.
+ */
+
+void SHA_Init(SHA_State * s)
+{
+ SHA_Core_Init(s->h);
+ s->blkused = 0;
+ s->lenhi = s->lenlo = 0;
+}
+
+void SHA_Bytes(SHA_State * s, const void *p, int len)
+{
+ unsigned char *q = (unsigned char *) p;
+ uint32 wordblock[16];
+ uint32 lenw = len;
+ int i;
+
+ /*
+ * Update the length field.
+ */
+ s->lenlo += lenw;
+ s->lenhi += (s->lenlo < lenw);
+
+ if (s->blkused && s->blkused + len < 64) {
+ /*
+ * Trivial case: just add to the block.
+ */
+ memcpy(s->block + s->blkused, q, len);
+ s->blkused += len;
+ } else {
+ /*
+ * We must complete and process at least one block.
+ */
+ while (s->blkused + len >= 64) {
+ memcpy(s->block + s->blkused, q, 64 - s->blkused);
+ q += 64 - s->blkused;
+ len -= 64 - s->blkused;
+ /* Now process the block. Gather bytes big-endian into words */
+ for (i = 0; i < 16; i++) {
+ wordblock[i] =
+ (((uint32) s->block[i * 4 + 0]) << 24) |
+ (((uint32) s->block[i * 4 + 1]) << 16) |
+ (((uint32) s->block[i * 4 + 2]) << 8) |
+ (((uint32) s->block[i * 4 + 3]) << 0);
+ }
+ SHATransform(s->h, wordblock);
+ s->blkused = 0;
+ }
+ memcpy(s->block, q, len);
+ s->blkused = len;
+ }
+}
+
+void SHA_Final(SHA_State * s, unsigned char *output)
+{
+ int i;
+ int pad;
+ unsigned char c[64];
+ uint32 lenhi, lenlo;
+
+ if (s->blkused >= 56)
+ pad = 56 + 64 - s->blkused;
+ else
+ pad = 56 - s->blkused;
+
+ lenhi = (s->lenhi << 3) | (s->lenlo >> (32 - 3));
+ lenlo = (s->lenlo << 3);
+
+ memset(c, 0, pad);
+ c[0] = 0x80;
+ SHA_Bytes(s, &c, pad);
+
+ c[0] = (unsigned char)((lenhi >> 24) & 0xFF);
+ c[1] = (unsigned char)((lenhi >> 16) & 0xFF);
+ c[2] = (unsigned char)((lenhi >> 8) & 0xFF);
+ c[3] = (unsigned char)((lenhi >> 0) & 0xFF);
+ c[4] = (unsigned char)((lenlo >> 24) & 0xFF);
+ c[5] = (unsigned char)((lenlo >> 16) & 0xFF);
+ c[6] = (unsigned char)((lenlo >> 8) & 0xFF);
+ c[7] = (unsigned char)((lenlo >> 0) & 0xFF);
+
+ SHA_Bytes(s, &c, 8);
+
+ for (i = 0; i < 5; i++) {
+ output[i * 4] = (unsigned char)((s->h[i] >> 24) & 0xFF);
+ output[i * 4 + 1] = (unsigned char)((s->h[i] >> 16) & 0xFF);
+ output[i * 4 + 2] = (unsigned char)((s->h[i] >> 8) & 0xFF);
+ output[i * 4 + 3] = (unsigned char)((s->h[i]) & 0xFF);
+ }
+}
+
+void SHA_Simple(const void *p, int len, unsigned char *output)
+{
+ SHA_State s;
+
+ SHA_Init(&s);
+ SHA_Bytes(&s, p, len);
+ SHA_Final(&s, output);
+}
+
+/* ----------------------------------------------------------------------
+ * The random number generator.
+ */
+
+struct random_state {
+ unsigned char seedbuf[40];
+ unsigned char databuf[20];
+ int pos;
+};
+
+random_state *random_new(const char *seed, int len)
+{
+ random_state *state;
+
+ state = snew(random_state);
+
+ SHA_Simple(seed, len, state->seedbuf);
+ SHA_Simple(state->seedbuf, 20, state->seedbuf + 20);
+ SHA_Simple(state->seedbuf, 40, state->databuf);
+ state->pos = 0;
+
+ return state;
+}
+
+random_state *random_copy(random_state *tocopy)
+{
+ random_state *result;
+ result = snew(random_state);
+ memcpy(result->seedbuf, tocopy->seedbuf, sizeof(result->seedbuf));
+ memcpy(result->databuf, tocopy->databuf, sizeof(result->databuf));
+ result->pos = tocopy->pos;
+ return result;
+}
+
+unsigned long random_bits(random_state *state, int bits)
+{
+ unsigned long ret = 0;
+ int n;
+
+ for (n = 0; n < bits; n += 8) {
+ if (state->pos >= 20) {
+ int i;
+
+ for (i = 0; i < 20; i++) {
+ if (state->seedbuf[i] != 0xFF) {
+ state->seedbuf[i]++;
+ break;
+ } else
+ state->seedbuf[i] = 0;
+ }
+ SHA_Simple(state->seedbuf, 40, state->databuf);
+ state->pos = 0;
+ }
+ ret = (ret << 8) | state->databuf[state->pos++];
+ }
+
+ /*
+ * `(1 << bits) - 1' is not good enough, since if bits==32 on a
+ * 32-bit machine, behaviour is undefined and Intel has a nasty
+ * habit of shifting left by zero instead. We'll shift by
+ * bits-1 and then separately shift by one.
+ */
+ ret &= (1 << (bits-1)) * 2 - 1;
+ return ret;
+}
+
+unsigned long random_upto(random_state *state, unsigned long limit)
+{
+ int bits = 0;
+ unsigned long max, divisor, data;
+
+ while ((limit >> bits) != 0)
+ bits++;
+
+ bits += 3;
+ //assert(bits < 32);
+
+ max = 1L << bits;
+ divisor = max / limit;
+ max = limit * divisor;
+
+ do {
+ data = random_bits(state, bits);
+ } while (data >= max);
+
+ return data / divisor;
+}
+
+void random_free(random_state *state)
+{
+ sfree(state);
+}
+
+char *random_state_encode(random_state *state)
+{
+ char retbuf[256];
+ int len = 0, i;
+
+ for (i = 0; i < lenof(state->seedbuf); i++)
+ len += sprintf(retbuf+len, "%02x", state->seedbuf[i]);
+ for (i = 0; i < lenof(state->databuf); i++)
+ len += sprintf(retbuf+len, "%02x", state->databuf[i]);
+ len += sprintf(retbuf+len, "%02x", state->pos);
+
+ return dupstr(retbuf);
+}
+
+random_state *random_state_decode(const char *input)
+{
+ random_state *state;
+ int pos, byte, digits;
+
+ state = snew(random_state);
+
+ memset(state->seedbuf, 0, sizeof(state->seedbuf));
+ memset(state->databuf, 0, sizeof(state->databuf));
+ state->pos = 0;
+
+ byte = digits = 0;
+ pos = 0;
+ while (*input) {
+ int v = *input++;
+
+ if (v >= '0' && v <= '9')
+ v = v - '0';
+ else if (v >= 'A' && v <= 'F')
+ v = v - 'A' + 10;
+ else if (v >= 'a' && v <= 'f')
+ v = v - 'a' + 10;
+ else
+ v = 0;
+
+ byte = (byte << 4) | v;
+ digits++;
+
+ if (digits == 2) {
+ /*
+ * We have a byte. Put it somewhere.
+ */
+ if (pos < lenof(state->seedbuf))
+ state->seedbuf[pos++] = byte;
+ else if (pos < lenof(state->seedbuf) + lenof(state->databuf))
+ state->databuf[pos++ - lenof(state->seedbuf)] = byte;
+ else if (pos == lenof(state->seedbuf) + lenof(state->databuf) &&
+ byte <= lenof(state->databuf))
+ state->pos = byte;
+ byte = digits = 0;
+ }
+ }
+
+ return state;
+}
generated by cgit v1.1 at 2026-04-25 10:34:22 +0000