1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
|
// This file is used to provide a "just enough" implementation of some C standard library functions
// required by Embedded target builds.
#include <stdint.h>
#include <stddef.h>
#define WASM_PAGE_SIZE 0x10000
size_t __builtin_wasm_memory_grow(int32_t index, size_t delta);
void *__builtin_memcpy(void *dest, const void *src, size_t n);
static void* alignedAlloc(size_t alignment, size_t size) {
size_t basePageSize = __builtin_wasm_memory_grow(0, (size + 0xffff) / 0x10000);
if (basePageSize == (size_t)-1) {
return NULL;
}
size_t base = basePageSize * WASM_PAGE_SIZE;
base = (base + alignment - 1) & -alignment;
return (void*)base;
}
/// NOTE: always allocates a new memory page by `memory.grow`
int posix_memalign(void** memptr, size_t alignment, size_t size) {
void* ptr = alignedAlloc(alignment, size);
if (ptr == NULL) {
return -1;
}
*memptr = ptr;
return 0;
}
/// NOTE: always allocates a new memory page by `memory.grow` and copies the old data
void* cabi_realloc(void* old, size_t oldSize, size_t align, size_t newSize) {
if (old != NULL) {
void* new = alignedAlloc(align, newSize);
if (new != NULL) {
__builtin_memcpy(new, old, oldSize < newSize ? oldSize : newSize);
}
return new;
} else {
return alignedAlloc(align, newSize);
}
}
void *memmove(void *dest, const void *src, size_t n) {
return __builtin_memcpy(dest, src, n);
}
void *memcpy(void *dest, const void *src, size_t n) {
// `memory.copy` is safe even if `src` and `dest` overlap
// > Copying takes place as if an intermediate buffer were used, allowing the destination and source to overlap.
// > https://github.com/WebAssembly/bulk-memory-operations/blob/master/proposals/bulk-memory-operations/Overview.md
return __builtin_memcpy(dest, src, n);
}
/// NOTE: does nothing as we don't manage memory chunks
void free(void *ptr) {}
/// NOTE: just returns the input character as is, no output is produced
int putchar(int c) {
return c;
}
/// NOTE: fills the buffer with a constant value
void arc4random_buf(void *buf, size_t n) {
for (size_t i = 0; i < n; i++) {
((uint8_t *)buf)[i] = (uint8_t)42;
}
}
|
