| 24 | */ |
| 25 | |
| 26 | void *memalign(size_t align, size_t len) |
| 27 | { |
| 28 | unsigned char *mem, *new, *end; |
| 29 | size_t header, footer; |
| 30 | |
| 31 | if ((align & -align) != align) { |
| 32 | errno = EINVAL; |
| 33 | return NULL; |
| 34 | } |
| 35 | |
| 36 | if (len > SIZE_MAX - align) { |
| 37 | errno = ENOMEM; |
| 38 | return NULL; |
| 39 | } |
| 40 | |
| 41 | if (align <= 4*sizeof(size_t)) { |
| 42 | if (!(mem = malloc(len))) |
| 43 | return NULL; |
| 44 | return mem; |
| 45 | } |
| 46 | |
| 47 | if (!(mem = malloc(len + align-1))) |
| 48 | return NULL; |
| 49 | |
| 50 | new = (void *)((uintptr_t)mem + align-1 & -align); |
| 51 | if (new == mem) return mem; |
| 52 | |
| 53 | header = ((size_t *)mem)[-1]; |
| 54 | |
| 55 | if (!(header & 7)) { |
| 56 | ((size_t *)new)[-2] = ((size_t *)mem)[-2] + (new-mem); |
| 57 | ((size_t *)new)[-1] = ((size_t *)mem)[-1] - (new-mem); |
| 58 | return new; |
| 59 | } |
| 60 | |
| 61 | end = mem + (header & -8); |
| 62 | footer = ((size_t *)end)[-2]; |
| 63 | |
| 64 | ((size_t *)mem)[-1] = (header&7) | new-mem; |
| 65 | ((size_t *)new)[-2] = (footer&7) | new-mem; |
| 66 | ((size_t *)new)[-1] = (header&7) | end-new; |
| 67 | ((size_t *)end)[-2] = (footer&7) | end-new; |
| 68 | |
| 69 | free(mem); |
| 70 | return new; |
| 71 | } |