Messages in this thread | | | Date | Fri, 29 Aug 2003 15:03:35 -0600 | From | Erik Andersen <> | Subject | Re: [PATCHSET][2.6-test4][0/6]Support for HPET based timer - Take 2 |
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On Fri Aug 29, 2003 at 11:23:47AM -0700, Andrew Morton wrote: > "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com> wrote: > > > > Resending the patch. > > Thanks, I'll include these in the next -mm kernel. > > Reading the code, the only thing which leaps out is: > > +/* Use our own asm for 64 bit multiply/divide */ > +#define ASM_MUL64_REG(eax_out,edx_out,reg_in,eax_in) \ > + __asm__ __volatile__("mull %2" \ > + :"=a" (eax_out), "=d" (edx_out) \ > + :"r" (reg_in), "0" (eax_in)) > + > +#define ASM_DIV64_REG(eax_out,edx_out,reg_in,eax_in,edx_in) \ > + __asm__ __volatile__("divl %2" \ > + :"=a" (eax_out), "=d" (edx_out) \ > + :"r" (reg_in), "0" (eax_in), "1" (edx_in)) > > We seem to keep on proliferating home-grown x86 64-bit math functions. > > Do you really need these? Is it possible to use do_div() and the C 64x64 > `*' operator instead?
The fundamental reason these are proliferating is that given some random bit of code such as:
u64 foo=9, bar=3, baz; baz = foo / bar; baz = foo % bar;
gcc then generates code calling __udivdi3 and __umoddi3. Since the kernel does not provide these, people keep reinventing them. Perhaps it is time to kill off do_div and all its little friends and simply copy __udivdi3 and __umoddi3 from libgcc.....
-Erik
-- Erik B. Andersen http://codepoet-consulting.com/ --This message was written using 73% post-consumer electrons-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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