| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | #ifndef __ASM_ARM_DIV64 |
| 2 | #define __ASM_ARM_DIV64 |
| 3 | |
| 4 | #include <asm/system.h> |
| 5 | |
| 6 | /* |
| 7 | * The semantics of do_div() are: |
| 8 | * |
| 9 | * uint32_t do_div(uint64_t *n, uint32_t base) |
| 10 | * { |
| 11 | * uint32_t remainder = *n % base; |
| 12 | * *n = *n / base; |
| 13 | * return remainder; |
| 14 | * } |
| 15 | * |
| 16 | * In other words, a 64-bit dividend with a 32-bit divisor producing |
| 17 | * a 64-bit result and a 32-bit remainder. To accomplish this optimally |
| 18 | * we call a special __do_div64 helper with completely non standard |
| 19 | * calling convention for arguments and results (beware). |
| 20 | */ |
| 21 | |
| 22 | #ifdef __ARMEB__ |
| 23 | #define __xh "r0" |
| 24 | #define __xl "r1" |
| 25 | #else |
| 26 | #define __xl "r0" |
| 27 | #define __xh "r1" |
| 28 | #endif |
| 29 | |
| 30 | #define do_div(n,base) \ |
| 31 | ({ \ |
| 32 | register unsigned int __base asm("r4") = base; \ |
| 33 | register unsigned long long __n asm("r0") = n; \ |
| 34 | register unsigned long long __res asm("r2"); \ |
| 35 | register unsigned int __rem asm(__xh); \ |
| 36 | asm( __asmeq("%0", __xh) \ |
| 37 | __asmeq("%1", "r2") \ |
| 38 | __asmeq("%2", "r0") \ |
| 39 | __asmeq("%3", "r4") \ |
| 40 | "bl __do_div64" \ |
| 41 | : "=r" (__rem), "=r" (__res) \ |
| 42 | : "r" (__n), "r" (__base) \ |
| 43 | : "ip", "lr", "cc"); \ |
| 44 | n = __res; \ |
| 45 | __rem; \ |
| 46 | }) |
| 47 | |
| 48 | #endif |