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Diffstat (limited to 'apps/plugins/puzzles/src/random.c')
-rw-r--r-- | apps/plugins/puzzles/src/random.c | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/apps/plugins/puzzles/src/random.c b/apps/plugins/puzzles/src/random.c new file mode 100644 index 0000000000..fb54560c95 --- /dev/null +++ b/apps/plugins/puzzles/src/random.c | |||
@@ -0,0 +1,351 @@ | |||
1 | /* | ||
2 | * random.c: Internal random number generator, guaranteed to work | ||
3 | * the same way on all platforms. Used when generating an initial | ||
4 | * game state from a random game seed; required to ensure that game | ||
5 | * seeds can be exchanged between versions of a puzzle compiled for | ||
6 | * different platforms. | ||
7 | * | ||
8 | * The generator is based on SHA-1. This is almost certainly | ||
9 | * overkill, but I had the SHA-1 code kicking around and it was | ||
10 | * easier to reuse it than to do anything else! | ||
11 | */ | ||
12 | |||
13 | #include <assert.h> | ||
14 | #include <string.h> | ||
15 | #include <stdio.h> | ||
16 | |||
17 | #include "puzzles.h" | ||
18 | |||
19 | /* ---------------------------------------------------------------------- | ||
20 | * Core SHA algorithm: processes 16-word blocks into a message digest. | ||
21 | */ | ||
22 | |||
23 | #define rol(x,y) ( ((x) << (y)) | (((uint32)x) >> (32-y)) ) | ||
24 | |||
25 | static void SHA_Core_Init(uint32 h[5]) | ||
26 | { | ||
27 | h[0] = 0x67452301; | ||
28 | h[1] = 0xefcdab89; | ||
29 | h[2] = 0x98badcfe; | ||
30 | h[3] = 0x10325476; | ||
31 | h[4] = 0xc3d2e1f0; | ||
32 | } | ||
33 | |||
34 | static void SHATransform(uint32 * digest, uint32 * block) | ||
35 | { | ||
36 | uint32 w[80]; | ||
37 | uint32 a, b, c, d, e; | ||
38 | int t; | ||
39 | |||
40 | for (t = 0; t < 16; t++) | ||
41 | w[t] = block[t]; | ||
42 | |||
43 | for (t = 16; t < 80; t++) { | ||
44 | uint32 tmp = w[t - 3] ^ w[t - 8] ^ w[t - 14] ^ w[t - 16]; | ||
45 | w[t] = rol(tmp, 1); | ||
46 | } | ||
47 | |||
48 | a = digest[0]; | ||
49 | b = digest[1]; | ||
50 | c = digest[2]; | ||
51 | d = digest[3]; | ||
52 | e = digest[4]; | ||
53 | |||
54 | for (t = 0; t < 20; t++) { | ||
55 | uint32 tmp = | ||
56 | rol(a, 5) + ((b & c) | (d & ~b)) + e + w[t] + 0x5a827999; | ||
57 | e = d; | ||
58 | d = c; | ||
59 | c = rol(b, 30); | ||
60 | b = a; | ||
61 | a = tmp; | ||
62 | } | ||
63 | for (t = 20; t < 40; t++) { | ||
64 | uint32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0x6ed9eba1; | ||
65 | e = d; | ||
66 | d = c; | ||
67 | c = rol(b, 30); | ||
68 | b = a; | ||
69 | a = tmp; | ||
70 | } | ||
71 | for (t = 40; t < 60; t++) { | ||
72 | uint32 tmp = rol(a, | ||
73 | 5) + ((b & c) | (b & d) | (c & d)) + e + w[t] + | ||
74 | 0x8f1bbcdc; | ||
75 | e = d; | ||
76 | d = c; | ||
77 | c = rol(b, 30); | ||
78 | b = a; | ||
79 | a = tmp; | ||
80 | } | ||
81 | for (t = 60; t < 80; t++) { | ||
82 | uint32 tmp = rol(a, 5) + (b ^ c ^ d) + e + w[t] + 0xca62c1d6; | ||
83 | e = d; | ||
84 | d = c; | ||
85 | c = rol(b, 30); | ||
86 | b = a; | ||
87 | a = tmp; | ||
88 | } | ||
89 | |||
90 | digest[0] += a; | ||
91 | digest[1] += b; | ||
92 | digest[2] += c; | ||
93 | digest[3] += d; | ||
94 | digest[4] += e; | ||
95 | } | ||
96 | |||
97 | /* ---------------------------------------------------------------------- | ||
98 | * Outer SHA algorithm: take an arbitrary length byte string, | ||
99 | * convert it into 16-word blocks with the prescribed padding at | ||
100 | * the end, and pass those blocks to the core SHA algorithm. | ||
101 | */ | ||
102 | |||
103 | void SHA_Init(SHA_State * s) | ||
104 | { | ||
105 | SHA_Core_Init(s->h); | ||
106 | s->blkused = 0; | ||
107 | s->lenhi = s->lenlo = 0; | ||
108 | } | ||
109 | |||
110 | void SHA_Bytes(SHA_State * s, const void *p, int len) | ||
111 | { | ||
112 | unsigned char *q = (unsigned char *) p; | ||
113 | uint32 wordblock[16]; | ||
114 | uint32 lenw = len; | ||
115 | int i; | ||
116 | |||
117 | /* | ||
118 | * Update the length field. | ||
119 | */ | ||
120 | s->lenlo += lenw; | ||
121 | s->lenhi += (s->lenlo < lenw); | ||
122 | |||
123 | if (s->blkused && s->blkused + len < 64) { | ||
124 | /* | ||
125 | * Trivial case: just add to the block. | ||
126 | */ | ||
127 | memcpy(s->block + s->blkused, q, len); | ||
128 | s->blkused += len; | ||
129 | } else { | ||
130 | /* | ||
131 | * We must complete and process at least one block. | ||
132 | */ | ||
133 | while (s->blkused + len >= 64) { | ||
134 | memcpy(s->block + s->blkused, q, 64 - s->blkused); | ||
135 | q += 64 - s->blkused; | ||
136 | len -= 64 - s->blkused; | ||
137 | /* Now process the block. Gather bytes big-endian into words */ | ||
138 | for (i = 0; i < 16; i++) { | ||
139 | wordblock[i] = | ||
140 | (((uint32) s->block[i * 4 + 0]) << 24) | | ||
141 | (((uint32) s->block[i * 4 + 1]) << 16) | | ||
142 | (((uint32) s->block[i * 4 + 2]) << 8) | | ||
143 | (((uint32) s->block[i * 4 + 3]) << 0); | ||
144 | } | ||
145 | SHATransform(s->h, wordblock); | ||
146 | s->blkused = 0; | ||
147 | } | ||
148 | memcpy(s->block, q, len); | ||
149 | s->blkused = len; | ||
150 | } | ||
151 | } | ||
152 | |||
153 | void SHA_Final(SHA_State * s, unsigned char *output) | ||
154 | { | ||
155 | int i; | ||
156 | int pad; | ||
157 | unsigned char c[64]; | ||
158 | uint32 lenhi, lenlo; | ||
159 | |||
160 | if (s->blkused >= 56) | ||
161 | pad = 56 + 64 - s->blkused; | ||
162 | else | ||
163 | pad = 56 - s->blkused; | ||
164 | |||
165 | lenhi = (s->lenhi << 3) | (s->lenlo >> (32 - 3)); | ||
166 | lenlo = (s->lenlo << 3); | ||
167 | |||
168 | memset(c, 0, pad); | ||
169 | c[0] = 0x80; | ||
170 | SHA_Bytes(s, &c, pad); | ||
171 | |||
172 | c[0] = (unsigned char)((lenhi >> 24) & 0xFF); | ||
173 | c[1] = (unsigned char)((lenhi >> 16) & 0xFF); | ||
174 | c[2] = (unsigned char)((lenhi >> 8) & 0xFF); | ||
175 | c[3] = (unsigned char)((lenhi >> 0) & 0xFF); | ||
176 | c[4] = (unsigned char)((lenlo >> 24) & 0xFF); | ||
177 | c[5] = (unsigned char)((lenlo >> 16) & 0xFF); | ||
178 | c[6] = (unsigned char)((lenlo >> 8) & 0xFF); | ||
179 | c[7] = (unsigned char)((lenlo >> 0) & 0xFF); | ||
180 | |||
181 | SHA_Bytes(s, &c, 8); | ||
182 | |||
183 | for (i = 0; i < 5; i++) { | ||
184 | output[i * 4] = (unsigned char)((s->h[i] >> 24) & 0xFF); | ||
185 | output[i * 4 + 1] = (unsigned char)((s->h[i] >> 16) & 0xFF); | ||
186 | output[i * 4 + 2] = (unsigned char)((s->h[i] >> 8) & 0xFF); | ||
187 | output[i * 4 + 3] = (unsigned char)((s->h[i]) & 0xFF); | ||
188 | } | ||
189 | } | ||
190 | |||
191 | void SHA_Simple(const void *p, int len, unsigned char *output) | ||
192 | { | ||
193 | SHA_State s; | ||
194 | |||
195 | SHA_Init(&s); | ||
196 | SHA_Bytes(&s, p, len); | ||
197 | SHA_Final(&s, output); | ||
198 | } | ||
199 | |||
200 | /* ---------------------------------------------------------------------- | ||
201 | * The random number generator. | ||
202 | */ | ||
203 | |||
204 | struct random_state { | ||
205 | unsigned char seedbuf[40]; | ||
206 | unsigned char databuf[20]; | ||
207 | int pos; | ||
208 | }; | ||
209 | |||
210 | random_state *random_new(const char *seed, int len) | ||
211 | { | ||
212 | random_state *state; | ||
213 | |||
214 | state = snew(random_state); | ||
215 | |||
216 | SHA_Simple(seed, len, state->seedbuf); | ||
217 | SHA_Simple(state->seedbuf, 20, state->seedbuf + 20); | ||
218 | SHA_Simple(state->seedbuf, 40, state->databuf); | ||
219 | state->pos = 0; | ||
220 | |||
221 | return state; | ||
222 | } | ||
223 | |||
224 | random_state *random_copy(random_state *tocopy) | ||
225 | { | ||
226 | random_state *result; | ||
227 | result = snew(random_state); | ||
228 | memcpy(result->seedbuf, tocopy->seedbuf, sizeof(result->seedbuf)); | ||
229 | memcpy(result->databuf, tocopy->databuf, sizeof(result->databuf)); | ||
230 | result->pos = tocopy->pos; | ||
231 | return result; | ||
232 | } | ||
233 | |||
234 | unsigned long random_bits(random_state *state, int bits) | ||
235 | { | ||
236 | unsigned long ret = 0; | ||
237 | int n; | ||
238 | |||
239 | for (n = 0; n < bits; n += 8) { | ||
240 | if (state->pos >= 20) { | ||
241 | int i; | ||
242 | |||
243 | for (i = 0; i < 20; i++) { | ||
244 | if (state->seedbuf[i] != 0xFF) { | ||
245 | state->seedbuf[i]++; | ||
246 | break; | ||
247 | } else | ||
248 | state->seedbuf[i] = 0; | ||
249 | } | ||
250 | SHA_Simple(state->seedbuf, 40, state->databuf); | ||
251 | state->pos = 0; | ||
252 | } | ||
253 | ret = (ret << 8) | state->databuf[state->pos++]; | ||
254 | } | ||
255 | |||
256 | /* | ||
257 | * `(1 << bits) - 1' is not good enough, since if bits==32 on a | ||
258 | * 32-bit machine, behaviour is undefined and Intel has a nasty | ||
259 | * habit of shifting left by zero instead. We'll shift by | ||
260 | * bits-1 and then separately shift by one. | ||
261 | */ | ||
262 | ret &= (1 << (bits-1)) * 2 - 1; | ||
263 | return ret; | ||
264 | } | ||
265 | |||
266 | unsigned long random_upto(random_state *state, unsigned long limit) | ||
267 | { | ||
268 | int bits = 0; | ||
269 | unsigned long max, divisor, data; | ||
270 | |||
271 | while ((limit >> bits) != 0) | ||
272 | bits++; | ||
273 | |||
274 | bits += 3; | ||
275 | assert(bits < 32); | ||
276 | |||
277 | max = 1L << bits; | ||
278 | divisor = max / limit; | ||
279 | max = limit * divisor; | ||
280 | |||
281 | do { | ||
282 | data = random_bits(state, bits); | ||
283 | } while (data >= max); | ||
284 | |||
285 | return data / divisor; | ||
286 | } | ||
287 | |||
288 | void random_free(random_state *state) | ||
289 | { | ||
290 | sfree(state); | ||
291 | } | ||
292 | |||
293 | char *random_state_encode(random_state *state) | ||
294 | { | ||
295 | char retbuf[256]; | ||
296 | int len = 0, i; | ||
297 | |||
298 | for (i = 0; i < lenof(state->seedbuf); i++) | ||
299 | len += sprintf(retbuf+len, "%02x", state->seedbuf[i]); | ||
300 | for (i = 0; i < lenof(state->databuf); i++) | ||
301 | len += sprintf(retbuf+len, "%02x", state->databuf[i]); | ||
302 | len += sprintf(retbuf+len, "%02x", state->pos); | ||
303 | |||
304 | return dupstr(retbuf); | ||
305 | } | ||
306 | |||
307 | random_state *random_state_decode(const char *input) | ||
308 | { | ||
309 | random_state *state; | ||
310 | int pos, byte, digits; | ||
311 | |||
312 | state = snew(random_state); | ||
313 | |||
314 | memset(state->seedbuf, 0, sizeof(state->seedbuf)); | ||
315 | memset(state->databuf, 0, sizeof(state->databuf)); | ||
316 | state->pos = 0; | ||
317 | |||
318 | byte = digits = 0; | ||
319 | pos = 0; | ||
320 | while (*input) { | ||
321 | int v = *input++; | ||
322 | |||
323 | if (v >= '0' && v <= '9') | ||
324 | v = v - '0'; | ||
325 | else if (v >= 'A' && v <= 'F') | ||
326 | v = v - 'A' + 10; | ||
327 | else if (v >= 'a' && v <= 'f') | ||
328 | v = v - 'a' + 10; | ||
329 | else | ||
330 | v = 0; | ||
331 | |||
332 | byte = (byte << 4) | v; | ||
333 | digits++; | ||
334 | |||
335 | if (digits == 2) { | ||
336 | /* | ||
337 | * We have a byte. Put it somewhere. | ||
338 | */ | ||
339 | if (pos < lenof(state->seedbuf)) | ||
340 | state->seedbuf[pos++] = byte; | ||
341 | else if (pos < lenof(state->seedbuf) + lenof(state->databuf)) | ||
342 | state->databuf[pos++ - lenof(state->seedbuf)] = byte; | ||
343 | else if (pos == lenof(state->seedbuf) + lenof(state->databuf) && | ||
344 | byte <= lenof(state->databuf)) | ||
345 | state->pos = byte; | ||
346 | byte = digits = 0; | ||
347 | } | ||
348 | } | ||
349 | |||
350 | return state; | ||
351 | } | ||