| #include <stdlib.h> |
| #include <stdint.h> |
| #include <errno.h> |
| #include "libc.h" |
| |
| /* This function should work with most dlmalloc-like chunk bookkeeping |
| * systems, but it's only guaranteed to work with the native implementation |
| * used in this library. */ |
| |
| void *__memalign(size_t align, size_t len) |
| { |
| unsigned char *mem, *new, *end; |
| size_t header, footer; |
| |
| if ((align & -align) != align) { |
| errno = EINVAL; |
| return NULL; |
| } |
| |
| if (len > SIZE_MAX - align) { |
| errno = ENOMEM; |
| return NULL; |
| } |
| |
| if (align <= 4*sizeof(size_t)) { |
| if (!(mem = malloc(len))) |
| return NULL; |
| return mem; |
| } |
| |
| if (!(mem = malloc(len + align-1))) |
| return NULL; |
| |
| new = (void *)((uintptr_t)mem + align-1 & -align); |
| if (new == mem) return mem; |
| |
| header = ((size_t *)mem)[-1]; |
| |
| if (!(header & 7)) { |
| ((size_t *)new)[-2] = ((size_t *)mem)[-2] + (new-mem); |
| ((size_t *)new)[-1] = ((size_t *)mem)[-1] - (new-mem); |
| return new; |
| } |
| |
| end = mem + (header & -8); |
| footer = ((size_t *)end)[-2]; |
| |
| ((size_t *)mem)[-1] = header&7 | new-mem; |
| ((size_t *)new)[-2] = footer&7 | new-mem; |
| ((size_t *)new)[-1] = header&7 | end-new; |
| ((size_t *)end)[-2] = footer&7 | end-new; |
| |
| free(mem); |
| return new; |
| } |
| |
| weak_alias(__memalign, memalign); |