diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
---|---|---|
committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-i386/div64.h | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'include/asm-i386/div64.h')
-rw-r--r-- | include/asm-i386/div64.h | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/include/asm-i386/div64.h b/include/asm-i386/div64.h new file mode 100644 index 000000000000..28ed8b296afc --- /dev/null +++ b/include/asm-i386/div64.h @@ -0,0 +1,48 @@ +#ifndef __I386_DIV64 +#define __I386_DIV64 + +/* + * do_div() is NOT a C function. It wants to return + * two values (the quotient and the remainder), but + * since that doesn't work very well in C, what it + * does is: + * + * - modifies the 64-bit dividend _in_place_ + * - returns the 32-bit remainder + * + * This ends up being the most efficient "calling + * convention" on x86. + */ +#define do_div(n,base) ({ \ + unsigned long __upper, __low, __high, __mod, __base; \ + __base = (base); \ + asm("":"=a" (__low), "=d" (__high):"A" (n)); \ + __upper = __high; \ + if (__high) { \ + __upper = __high % (__base); \ + __high = __high / (__base); \ + } \ + asm("divl %2":"=a" (__low), "=d" (__mod):"rm" (__base), "0" (__low), "1" (__upper)); \ + asm("":"=A" (n):"a" (__low),"d" (__high)); \ + __mod; \ +}) + +/* + * (long)X = ((long long)divs) / (long)div + * (long)rem = ((long long)divs) % (long)div + * + * Warning, this will do an exception if X overflows. + */ +#define div_long_long_rem(a,b,c) div_ll_X_l_rem(a,b,c) + +extern inline long +div_ll_X_l_rem(long long divs, long div, long *rem) +{ + long dum2; + __asm__("divl %2":"=a"(dum2), "=d"(*rem) + : "rm"(div), "A"(divs)); + + return dum2; + +} +#endif |