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 0000000000..c129a8d2ba
--- /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;
+}