libanim

annotate src/dynarr.c @ 37:c97151c60302

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libanim mercurial repo
author John Tsiombikas <nuclear@mutantstargoat.com>
date Sun, 08 Jan 2012 05:13:13 +0200
parents
children 60a46a122b0f
rev   line source
nuclear@0 1 #include <stdio.h>
nuclear@0 2 #include <stdlib.h>
nuclear@0 3 #include <string.h>
nuclear@0 4 #include "dynarr.h"
nuclear@0 5
nuclear@0 6 /* The array descriptor keeps auxilliary information needed to manipulate
nuclear@0 7 * the dynamic array. It's allocated adjacent to the array buffer.
nuclear@0 8 */
nuclear@0 9 struct arrdesc {
nuclear@0 10 int nelem, szelem;
nuclear@0 11 int max_elem;
nuclear@0 12 int bufsz; /* not including the descriptor */
nuclear@0 13 };
nuclear@0 14
nuclear@0 15 #define DESC(x) ((struct arrdesc*)((char*)(x) - sizeof(struct arrdesc)))
nuclear@0 16
nuclear@0 17 void *dynarr_alloc(int elem, int szelem)
nuclear@0 18 {
nuclear@0 19 struct arrdesc *desc;
nuclear@0 20
nuclear@0 21 if(!(desc = malloc(elem * szelem + sizeof *desc))) {
nuclear@0 22 return 0;
nuclear@0 23 }
nuclear@0 24 desc->nelem = desc->max_elem = elem;
nuclear@0 25 desc->szelem = szelem;
nuclear@0 26 desc->bufsz = elem * szelem;
nuclear@0 27 return (char*)desc + sizeof *desc;
nuclear@0 28 }
nuclear@0 29
nuclear@0 30 void dynarr_free(void *da)
nuclear@0 31 {
nuclear@0 32 if(da) {
nuclear@0 33 free(DESC(da));
nuclear@0 34 }
nuclear@0 35 }
nuclear@0 36
nuclear@0 37 void *dynarr_resize(void *da, int elem)
nuclear@0 38 {
nuclear@0 39 int newsz;
nuclear@0 40 void *tmp;
nuclear@0 41 struct arrdesc *desc;
nuclear@0 42
nuclear@0 43 if(!da) return 0;
nuclear@0 44 desc = DESC(da);
nuclear@0 45
nuclear@0 46 newsz = desc->szelem * elem;
nuclear@0 47
nuclear@0 48 if(!(tmp = realloc(desc, newsz + sizeof *desc))) {
nuclear@0 49 return 0;
nuclear@0 50 }
nuclear@0 51 desc = tmp;
nuclear@0 52
nuclear@0 53 desc->nelem = desc->max_elem = elem;
nuclear@0 54 desc->bufsz = newsz;
nuclear@0 55 return (char*)desc + sizeof *desc;
nuclear@0 56 }
nuclear@0 57
nuclear@0 58 int dynarr_empty(void *da)
nuclear@0 59 {
nuclear@0 60 return DESC(da)->nelem ? 0 : 1;
nuclear@0 61 }
nuclear@0 62
nuclear@0 63 int dynarr_size(void *da)
nuclear@0 64 {
nuclear@0 65 return DESC(da)->nelem;
nuclear@0 66 }
nuclear@0 67
nuclear@0 68
nuclear@0 69 /* stack semantics */
nuclear@0 70 void *dynarr_push(void *da, void *item)
nuclear@0 71 {
nuclear@0 72 struct arrdesc *desc;
nuclear@0 73 int nelem;
nuclear@0 74
nuclear@0 75 desc = DESC(da);
nuclear@0 76 nelem = desc->nelem;
nuclear@0 77
nuclear@0 78 if(nelem >= desc->max_elem) {
nuclear@0 79 /* need to resize */
nuclear@0 80 struct arrdesc *tmp;
nuclear@0 81 int newsz = desc->max_elem ? desc->max_elem * 2 : 1;
nuclear@0 82
nuclear@0 83 if(!(tmp = dynarr_resize(da, newsz))) {
nuclear@0 84 fprintf(stderr, "failed to resize\n");
nuclear@0 85 return da;
nuclear@0 86 }
nuclear@0 87 da = tmp;
nuclear@0 88 desc = DESC(da);
nuclear@0 89 desc->nelem = nelem;
nuclear@0 90 }
nuclear@0 91
nuclear@0 92 memcpy((char*)da + desc->nelem++ * desc->szelem, item, desc->szelem);
nuclear@0 93 return da;
nuclear@0 94 }
nuclear@0 95
nuclear@0 96 void *dynarr_pop(void *da)
nuclear@0 97 {
nuclear@0 98 struct arrdesc *desc;
nuclear@0 99 int nelem;
nuclear@0 100
nuclear@0 101 desc = DESC(da);
nuclear@0 102 nelem = desc->nelem;
nuclear@0 103
nuclear@0 104 if(!nelem) return da;
nuclear@0 105
nuclear@0 106 if(nelem <= desc->max_elem / 3) {
nuclear@0 107 /* reclaim space */
nuclear@0 108 struct arrdesc *tmp;
nuclear@0 109 int newsz = desc->max_elem / 2;
nuclear@0 110
nuclear@0 111 if(!(tmp = dynarr_resize(da, newsz))) {
nuclear@0 112 fprintf(stderr, "failed to resize\n");
nuclear@0 113 return da;
nuclear@0 114 }
nuclear@0 115 da = tmp;
nuclear@0 116 desc = DESC(da);
nuclear@0 117 desc->nelem = nelem;
nuclear@0 118 }
nuclear@0 119 desc->nelem--;
nuclear@0 120
nuclear@0 121 return da;
nuclear@0 122 }