[270] | 1 | /*
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| 2 | ** pool.c - memory pool
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| 3 | **
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| 4 | ** See Copyright Notice in mruby.h
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| 5 | */
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| 6 |
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| 7 | #include <stddef.h>
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| 8 | #include <stdint.h>
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| 9 | #include <string.h>
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| 10 | #include "mruby.h"
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| 11 |
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| 12 | /* configuration section */
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| 13 | /* allocated memory address should be multiple of POOL_ALIGNMENT */
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| 14 | /* or undef it if alignment does not matter */
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| 15 | #ifndef POOL_ALIGNMENT
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| 16 | #define POOL_ALIGNMENT 4
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| 17 | #endif
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| 18 | /* page size of memory pool */
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| 19 | #ifndef POOL_PAGE_SIZE
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| 20 | #define POOL_PAGE_SIZE 16000
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| 21 | #endif
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| 22 | /* end of configuration section */
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| 23 |
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| 24 | struct mrb_pool_page {
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| 25 | struct mrb_pool_page *next;
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| 26 | size_t offset;
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| 27 | size_t len;
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| 28 | void *last;
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| 29 | char page[];
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| 30 | };
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| 31 |
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| 32 | struct mrb_pool {
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| 33 | mrb_state *mrb;
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| 34 | struct mrb_pool_page *pages;
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| 35 | };
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| 36 |
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| 37 | #undef TEST_POOL
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| 38 | #ifdef TEST_POOL
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| 39 |
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| 40 | #define mrb_malloc_simple(m,s) malloc(s)
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| 41 | #define mrb_free(m,p) free(p)
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| 42 | #endif
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| 43 |
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| 44 | #ifdef POOL_ALIGNMENT
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| 45 | # define ALIGN_PADDING(x) ((SIZE_MAX - (x) + 1) & (POOL_ALIGNMENT - 1))
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| 46 | #else
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| 47 | # define ALIGN_PADDING(x) (0)
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| 48 | #endif
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| 49 |
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| 50 | MRB_API mrb_pool*
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| 51 | mrb_pool_open(mrb_state *mrb)
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| 52 | {
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| 53 | mrb_pool *pool = (mrb_pool *)mrb_malloc_simple(mrb, sizeof(mrb_pool));
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| 54 |
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| 55 | if (pool) {
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| 56 | pool->mrb = mrb;
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| 57 | pool->pages = NULL;
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| 58 | }
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| 59 |
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| 60 | return pool;
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| 61 | }
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| 62 |
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| 63 | MRB_API void
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| 64 | mrb_pool_close(mrb_pool *pool)
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| 65 | {
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| 66 | struct mrb_pool_page *page, *tmp;
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| 67 |
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| 68 | if (!pool) return;
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| 69 | page = pool->pages;
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| 70 | while (page) {
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| 71 | tmp = page;
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| 72 | page = page->next;
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| 73 | mrb_free(pool->mrb, tmp);
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| 74 | }
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| 75 | mrb_free(pool->mrb, pool);
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| 76 | }
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| 77 |
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| 78 | static struct mrb_pool_page*
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| 79 | page_alloc(mrb_pool *pool, size_t len)
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| 80 | {
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| 81 | struct mrb_pool_page *page;
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| 82 |
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| 83 | if (len < POOL_PAGE_SIZE)
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| 84 | len = POOL_PAGE_SIZE;
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| 85 | page = (struct mrb_pool_page *)mrb_malloc_simple(pool->mrb, sizeof(struct mrb_pool_page)+len);
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| 86 | if (page) {
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| 87 | page->offset = 0;
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| 88 | page->len = len;
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| 89 | }
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| 90 |
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| 91 | return page;
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| 92 | }
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| 93 |
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| 94 | MRB_API void*
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| 95 | mrb_pool_alloc(mrb_pool *pool, size_t len)
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| 96 | {
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| 97 | struct mrb_pool_page *page;
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| 98 | size_t n;
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| 99 |
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| 100 | if (!pool) return NULL;
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| 101 | len += ALIGN_PADDING(len);
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| 102 | page = pool->pages;
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| 103 | while (page) {
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| 104 | if (page->offset + len <= page->len) {
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| 105 | n = page->offset;
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| 106 | page->offset += len;
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| 107 | page->last = (char*)page->page+n;
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| 108 | return page->last;
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| 109 | }
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| 110 | page = page->next;
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| 111 | }
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| 112 | page = page_alloc(pool, len);
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| 113 | if (!page) return NULL;
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| 114 | page->offset = len;
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| 115 | page->next = pool->pages;
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| 116 | pool->pages = page;
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| 117 |
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| 118 | page->last = (void*)page->page;
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| 119 | return page->last;
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| 120 | }
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| 121 |
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| 122 | MRB_API mrb_bool
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| 123 | mrb_pool_can_realloc(mrb_pool *pool, void *p, size_t len)
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| 124 | {
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| 125 | struct mrb_pool_page *page;
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| 126 |
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| 127 | if (!pool) return FALSE;
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| 128 | len += ALIGN_PADDING(len);
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| 129 | page = pool->pages;
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| 130 | while (page) {
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| 131 | if (page->last == p) {
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| 132 | size_t beg;
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| 133 |
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| 134 | beg = (char*)p - page->page;
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| 135 | if (beg + len > page->len) return FALSE;
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| 136 | return TRUE;
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| 137 | }
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| 138 | page = page->next;
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| 139 | }
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| 140 | return FALSE;
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| 141 | }
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| 142 |
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| 143 | MRB_API void*
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| 144 | mrb_pool_realloc(mrb_pool *pool, void *p, size_t oldlen, size_t newlen)
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| 145 | {
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| 146 | struct mrb_pool_page *page;
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| 147 | void *np;
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| 148 |
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| 149 | if (!pool) return NULL;
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| 150 | oldlen += ALIGN_PADDING(oldlen);
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| 151 | newlen += ALIGN_PADDING(newlen);
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| 152 | page = pool->pages;
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| 153 | while (page) {
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| 154 | if (page->last == p) {
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| 155 | size_t beg;
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| 156 |
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| 157 | beg = (char*)p - page->page;
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| 158 | if (beg + oldlen != page->offset) break;
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| 159 | if (beg + newlen > page->len) {
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| 160 | page->offset = beg;
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| 161 | break;
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| 162 | }
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| 163 | page->offset = beg + newlen;
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| 164 | return p;
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| 165 | }
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| 166 | page = page->next;
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| 167 | }
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| 168 | np = mrb_pool_alloc(pool, newlen);
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| 169 | if (np == NULL) {
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| 170 | return NULL;
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| 171 | }
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| 172 | memcpy(np, p, oldlen);
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| 173 | return np;
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| 174 | }
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| 175 |
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| 176 | #ifdef TEST_POOL
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| 177 | int
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| 178 | main(void)
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| 179 | {
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| 180 | int i, len = 250;
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| 181 | mrb_pool *pool;
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| 182 | void *p;
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| 183 |
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| 184 | pool = mrb_pool_open(NULL);
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| 185 | p = mrb_pool_alloc(pool, len);
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| 186 | for (i=1; i<20; i++) {
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| 187 | printf("%p (len=%d) %ud\n", p, len, mrb_pool_can_realloc(pool, p, len*2));
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| 188 | p = mrb_pool_realloc(pool, p, len, len*2);
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| 189 | len *= 2;
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| 190 | }
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| 191 | mrb_pool_close(pool);
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| 192 | return 0;
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| 193 | }
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| 194 | #endif
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