74 lines
1.7 KiB
C
74 lines
1.7 KiB
C
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#include "wasm.h"
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extern unsigned char __heap_base;
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static size_t __heap_tail = (size_t) &__heap_base;
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static size_t __heap_mark = (size_t) &__heap_base;
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#define memory_size() __builtin_wasm_memory_size(0)
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#define memory_grow(delta) __builtin_wasm_memory_grow(0, delta)
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enum {
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_mem_flag_used = 0xbf82583a,
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_mem_flag_free = 0xab34d705
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};
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WASM_EXPORT void* __malloc(size_t n) {
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n += (8 - (n % 4)) % 4;
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// check if size is enough
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size_t total = __heap_tail + n + 3 * sizeof(size_t);
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size_t size = memory_size() << 16;
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if (total > size) {
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memory_grow((total >> 16) - (size >> 16) + 1);
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}
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unsigned int r = __heap_tail;
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*((size_t*) r) = n;
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r += sizeof(size_t);
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*((size_t*) r) =_mem_flag_used;
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r += sizeof(size_t);
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__heap_tail = r + n;
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*((size_t*) __heap_tail) = n;
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__heap_tail += sizeof(size_t);
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return (void*) r;
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}
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WASM_EXPORT void __free(void* p) {
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size_t n;
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// null case
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if (!p) return;
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size_t r=(size_t)p;
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r -= sizeof(size_t);
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// already free
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if (*((size_t*) r) != _mem_flag_used) {
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return;
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}
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// mark it as free
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size_t flag = _mem_flag_free;
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*((size_t*) r) = flag;
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// calc ptr_tail
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r -= sizeof(size_t);
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n = *(size_t*) r; // size of current block
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size_t ptr_tail = ((size_t) p) + n + sizeof(size_t);
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// if not at tail return without moving __heap_tail
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if (__heap_tail != ptr_tail) {
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return;
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}
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__heap_tail = r;
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while (r > (size_t) &__heap_base) {
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r -= sizeof(size_t);
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n = *(size_t*) r; // size of previous block
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r -= n;
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r -= sizeof(size_t);
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flag = *((size_t*) r);
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if (flag != _mem_flag_free) break;
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r -= sizeof(size_t);
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n = *(size_t*) r; // size of current block
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__heap_tail = r;
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}
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}
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uint8_t shared_out[256];
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WASM_EXPORT uint8_t* __get_shared_out() {
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return shared_out;
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}
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