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Diffstat (limited to 'include/asm-arm/div64.h')
| -rw-r--r-- | include/asm-arm/div64.h | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/include/asm-arm/div64.h b/include/asm-arm/div64.h new file mode 100644 index 000000000000..3682616804ca --- /dev/null +++ b/include/asm-arm/div64.h @@ -0,0 +1,48 @@ +#ifndef __ASM_ARM_DIV64 +#define __ASM_ARM_DIV64 + +#include <asm/system.h> + +/* + * The semantics of do_div() are: + * + * uint32_t do_div(uint64_t *n, uint32_t base) + * { + * uint32_t remainder = *n % base; + * *n = *n / base; + * return remainder; + * } + * + * In other words, a 64-bit dividend with a 32-bit divisor producing + * a 64-bit result and a 32-bit remainder. To accomplish this optimally + * we call a special __do_div64 helper with completely non standard + * calling convention for arguments and results (beware). + */ + +#ifdef __ARMEB__ +#define __xh "r0" +#define __xl "r1" +#else +#define __xl "r0" +#define __xh "r1" +#endif + +#define do_div(n,base) \ +({ \ + register unsigned int __base asm("r4") = base; \ + register unsigned long long __n asm("r0") = n; \ + register unsigned long long __res asm("r2"); \ + register unsigned int __rem asm(__xh); \ + asm( __asmeq("%0", __xh) \ + __asmeq("%1", "r2") \ + __asmeq("%2", "r0") \ + __asmeq("%3", "r4") \ + "bl __do_div64" \ + : "=r" (__rem), "=r" (__res) \ + : "r" (__n), "r" (__base) \ + : "ip", "lr", "cc"); \ + n = __res; \ + __rem; \ +}) + +#endif |