User:Ledrug/bits

From Rosetta Code

<lang c>#include <stdio.h>

  1. include <stdlib.h>
  2. include <math.h>
  1. define MAXD 8

/* Perlin-like noise */ inline double hashed(int *data, int len) {

  1. define rot(a, d) ((a << (d)) | (a >> (32 - d)))

unsigned int *d = (void*)data, h = 0x123456, tmp;

while (len--) { tmp = *d++; h += rot(h, 16) ^ (rot(tmp, 5) ^ h); }

h ^= rot(h, 7); h += rot(h, 11); h ^= rot(h, 17); h += rot(h, 25);

  1. undef rot

return (double)(int)h / (1U << 31); }

double scale[MAXD], scale_u[MAXD]; void noise_init() { int i; for (i = 1; i < MAXD; i++) { scale[i] = 1 / (1 + sqrt(i + 1)); scale_u[i] = scale[i] / sqrt(i + 1); } }

double noise(double *x, int d) {

  1. define sum(s, x) for (s = 0, j = 0; j < d; j++) s += x

register int i, j; int n[MAXD], o[MAXD], tmp; double s, r, t, ret, w; double u[MAXD], sk[MAXD];

sum(s, x[j]); s *= scale[d];

for (i = 0; i < d; i++) { // sk[i] = x[i] + s; t = x[i] + s; u[i] = t - (n[i] = floor(t)); o[i] = i; }

for (i = 0; i < d - 1; i++) for (j = i; j < d; j++) if (u[o[i]] < u[o[j]]) tmp = o[i], o[i] = o[j], o[j] = tmp;

ret = 0, r = 1, w = 1;

for (i = 0; i < d; i++) { s = u[o[i]] / w; t = s * s * (3 - 2 * s); ret += hashed(n, d) * (1 - t) * r; w *= s; if (!w) return ret;

r *= t; n[o[i]]++; } return ret + hashed(n, d) * r; }

double get_noise2(double x, double y) { int i, ws; double r = 0, v[2];

for (i = 1, ws = 0; i <= 256; i <<= 1) { v[0] = x * i, v[1] = y * i; r += noise(v, 2); ws ++; } r /= ws; return r; }

double get_noise3(double x, double y, double z) { int i, ws; double r = 0, v[3], w;

for (i = 1, ws = 0; i <= 128; i <<= 1) { v[0] = x * i, v[1] = y * i, v[2] = z * i; w = 1./sqrt(i); r += noise(v, 3) * w; ws += w; } return r / ws; }


int main() { unsigned char pix[256 * 256], *p; int i, j; double x, y, z, w; FILE *fp;

noise_init();

for (p = pix, i = 0; i < 256 * 256; i++) *p++ = 0;

get_noise2(0, .0001); for (p = pix, i = 0; i < 256; i++) { y = (i - 128) / 125.; for (j = 0; j < 256; j++, p++) { x = (j - 128) / 125.; *p = (get_noise2(i/256., j/256.) + 1) / 6 * i; //*p = (get_noise2(i/256., j/256.) + 1) / 2 * 255;

z = 1- x*x - y*y; if (z < 0) continue;

z = sqrt(z); w = get_noise3(x, y, z + 1); w = (w + 1) / 2; w = w * (.5 + x - y + z) / 3; if (w < 0) w = 0;

*p = w * 255; } }

fp = fopen("out.pgm", "w+"); fprintf(fp, "P5\n256 256\n255\n"); fwrite(pix, 1, 256 * 256, fp); fclose(fp);

return 0; }</lang> <lang c>#include <stdio.h>

  1. include <stdlib.h>
  2. include <stdint.h>
  3. include <string.h>

typedef uint32_t hash_t;

typedef struct hash_value_t { void *data; char *key; struct hash_value_t *chain; } hash_value_t;

typedef struct hash_table_t { hash_value_t **v, *pool; size_t n, cap; } hash_table_t, *htbl;

inline hash_t hash(char *s) { hash_t hash; for (hash = 0; *s; s++) { hash += *s; hash += (hash << 10); hash ^= (hash >> 6); } hash += hash << 3; hash ^= hash >> 11; hash += hash << 15; return hash; }

htbl hash_new(size_t size) { htbl h = calloc(1, sizeof(hash_table_t)); if (!size) size = 4;

for (h->cap = 1; h->cap < size; h->cap <<= 1);

h->v = calloc(h->cap, sizeof(hash_value_t*)); h->pool = 0; return h; }

hash_value_t *hash_get_storage(htbl t) { size_t len; hash_value_t *p = t->pool; if (!p) { len = 1024; if (len > t->cap) len = t->cap; t->pool = calloc(len, sizeof(hash_value_t)); for (p = t->pool; len > 1; len --) p->chain = p + 1; p = t->pool; } t->pool = p->chain; return p; }

void hash_insert_node(htbl t, hash_value_t *p) { size_t idx = hash(p->key) % t->cap; p->chain = t->v[idx]; t->v[idx] = p; }

void hash_expand(htbl t) { size_t i, c = t->cap; hash_value_t *p, *tmp;

t->v = realloc(t->v, sizeof(hash_value_t*) * c * 2); memset(t->v + c, 0, c * sizeof(hash_table_t*));

t->cap *= 2; for (i = 0; i < c; i++) { p = t->v[i]; if (!p) continue;

t->v[i] = 0; while (p) { tmp = p->chain; p->chain = 0; hash_insert_node(t, p); p = tmp; } } }

void hash_insert(htbl t, char *s, void *data) { hash_value_t *p = hash_get_storage(t); if (t->n * 5 >= t->cap * 4) hash_expand(t); p->key = strdup(s); p->data = data; hash_insert_node(t, p); t->n ++; }

void* hash_remove(htbl t, char *s) { size_t idx = hash(s) % t->cap; hash_value_t *head = 0, *p = t->v[idx];

while (p) { if (!strcmp(p->key, s)) break; head = p; p = p->chain; } if (!p) return 0;

free(p->key);

if (head) head->chain = p->chain; else t->v[idx] = p->chain;

p->chain = t->pool; t->pool = p; t->n--; return p->data; }

void* hash_lookup(htbl t, char *s) { size_t idx = hash(s) % t->cap; hash_value_t *p; p = t->v[idx]; while (p) { if (!strcmp(p->key, s)) return p->data; p = p->chain; } return (void*)-1; }</lang>

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