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annotate prototype/anim/dynarr.c @ 75:b05ab29cd17d

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color grading done
author John Tsiombikas <nuclear@member.fsf.org>
date Mon, 22 Oct 2012 03:55:00 +0300
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nuclear@67 1 #include <stdio.h>
nuclear@67 2 #include <stdlib.h>
nuclear@67 3 #include <string.h>
nuclear@67 4 #include "dynarr.h"
nuclear@67 5
nuclear@67 6 /* The array descriptor keeps auxilliary information needed to manipulate
nuclear@67 7 * the dynamic array. It's allocated adjacent to the array buffer.
nuclear@67 8 */
nuclear@67 9 struct arrdesc {
nuclear@67 10 int nelem, szelem;
nuclear@67 11 int max_elem;
nuclear@67 12 int bufsz; /* not including the descriptor */
nuclear@67 13 };
nuclear@67 14
nuclear@67 15 #define DESC(x) ((struct arrdesc*)((char*)(x) - sizeof(struct arrdesc)))
nuclear@67 16
nuclear@67 17 void *dynarr_alloc(int elem, int szelem)
nuclear@67 18 {
nuclear@67 19 struct arrdesc *desc;
nuclear@67 20
nuclear@67 21 if(!(desc = malloc(elem * szelem + sizeof *desc))) {
nuclear@67 22 return 0;
nuclear@67 23 }
nuclear@67 24 desc->nelem = desc->max_elem = elem;
nuclear@67 25 desc->szelem = szelem;
nuclear@67 26 desc->bufsz = elem * szelem;
nuclear@67 27 return (char*)desc + sizeof *desc;
nuclear@67 28 }
nuclear@67 29
nuclear@67 30 void dynarr_free(void *da)
nuclear@67 31 {
nuclear@67 32 if(da) {
nuclear@67 33 free(DESC(da));
nuclear@67 34 }
nuclear@67 35 }
nuclear@67 36
nuclear@67 37 void *dynarr_resize(void *da, int elem)
nuclear@67 38 {
nuclear@67 39 int newsz;
nuclear@67 40 void *tmp;
nuclear@67 41 struct arrdesc *desc;
nuclear@67 42
nuclear@67 43 if(!da) return 0;
nuclear@67 44 desc = DESC(da);
nuclear@67 45
nuclear@67 46 newsz = desc->szelem * elem;
nuclear@67 47
nuclear@67 48 if(!(tmp = realloc(desc, newsz + sizeof *desc))) {
nuclear@67 49 return 0;
nuclear@67 50 }
nuclear@67 51 desc = tmp;
nuclear@67 52
nuclear@67 53 desc->nelem = desc->max_elem = elem;
nuclear@67 54 desc->bufsz = newsz;
nuclear@67 55 return (char*)desc + sizeof *desc;
nuclear@67 56 }
nuclear@67 57
nuclear@67 58 int dynarr_empty(void *da)
nuclear@67 59 {
nuclear@67 60 return DESC(da)->nelem ? 0 : 1;
nuclear@67 61 }
nuclear@67 62
nuclear@67 63 int dynarr_size(void *da)
nuclear@67 64 {
nuclear@67 65 return DESC(da)->nelem;
nuclear@67 66 }
nuclear@67 67
nuclear@67 68
nuclear@67 69 /* stack semantics */
nuclear@67 70 void *dynarr_push(void *da, void *item)
nuclear@67 71 {
nuclear@67 72 struct arrdesc *desc;
nuclear@67 73 int nelem;
nuclear@67 74
nuclear@67 75 desc = DESC(da);
nuclear@67 76 nelem = desc->nelem;
nuclear@67 77
nuclear@67 78 if(nelem >= desc->max_elem) {
nuclear@67 79 /* need to resize */
nuclear@67 80 struct arrdesc *tmp;
nuclear@67 81 int newsz = desc->max_elem ? desc->max_elem * 2 : 1;
nuclear@67 82
nuclear@67 83 if(!(tmp = dynarr_resize(da, newsz))) {
nuclear@67 84 fprintf(stderr, "failed to resize\n");
nuclear@67 85 return da;
nuclear@67 86 }
nuclear@67 87 da = tmp;
nuclear@67 88 desc = DESC(da);
nuclear@67 89 desc->nelem = nelem;
nuclear@67 90 }
nuclear@67 91
nuclear@67 92 memcpy((char*)da + desc->nelem++ * desc->szelem, item, desc->szelem);
nuclear@67 93 return da;
nuclear@67 94 }
nuclear@67 95
nuclear@67 96 void *dynarr_pop(void *da)
nuclear@67 97 {
nuclear@67 98 struct arrdesc *desc;
nuclear@67 99 int nelem;
nuclear@67 100
nuclear@67 101 desc = DESC(da);
nuclear@67 102 nelem = desc->nelem;
nuclear@67 103
nuclear@67 104 if(!nelem) return da;
nuclear@67 105
nuclear@67 106 if(nelem <= desc->max_elem / 3) {
nuclear@67 107 /* reclaim space */
nuclear@67 108 struct arrdesc *tmp;
nuclear@67 109 int newsz = desc->max_elem / 2;
nuclear@67 110
nuclear@67 111 if(!(tmp = dynarr_resize(da, newsz))) {
nuclear@67 112 fprintf(stderr, "failed to resize\n");
nuclear@67 113 return da;
nuclear@67 114 }
nuclear@67 115 da = tmp;
nuclear@67 116 desc = DESC(da);
nuclear@67 117 desc->nelem = nelem;
nuclear@67 118 }
nuclear@67 119 desc->nelem--;
nuclear@67 120
nuclear@67 121 return da;
nuclear@67 122 }