74 lines
1.8 KiB
C
74 lines
1.8 KiB
C
/* asm/arch/bitops.h for Linux/CRISv10 */
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#ifndef _CRIS_ARCH_BITOPS_H
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#define _CRIS_ARCH_BITOPS_H
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/*
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* Helper functions for the core of the ff[sz] functions, wrapping the
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* syntactically awkward asms. The asms compute the number of leading
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* zeroes of a bits-in-byte and byte-in-word and word-in-dword-swapped
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* number. They differ in that the first function also inverts all bits
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* in the input.
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*/
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extern inline unsigned long cris_swapnwbrlz(unsigned long w)
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{
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/* Let's just say we return the result in the same register as the
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input. Saying we clobber the input but can return the result
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in another register:
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! __asm__ ("swapnwbr %2\n\tlz %2,%0"
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! : "=r,r" (res), "=r,X" (dummy) : "1,0" (w));
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confuses gcc (sched.c, gcc from cris-dist-1.14). */
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unsigned long res;
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__asm__ ("swapnwbr %0 \n\t"
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"lz %0,%0"
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: "=r" (res) : "0" (w));
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return res;
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}
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extern inline unsigned long cris_swapwbrlz(unsigned long w)
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{
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unsigned res;
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__asm__ ("swapwbr %0 \n\t"
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"lz %0,%0"
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: "=r" (res)
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: "0" (w));
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return res;
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}
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/*
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* ffz = Find First Zero in word. Undefined if no zero exists,
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* so code should check against ~0UL first..
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*/
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extern inline unsigned long ffz(unsigned long w)
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{
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return cris_swapnwbrlz(w);
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}
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/**
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* __ffs - find first bit in word.
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* @word: The word to search
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*
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* Undefined if no bit exists, so code should check against 0 first.
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*/
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extern inline unsigned long __ffs(unsigned long word)
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{
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return cris_swapnwbrlz(~word);
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}
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/**
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* ffs - find first bit set
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* @x: the word to search
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*
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* This is defined the same way as
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* the libc and compiler builtin ffs routines, therefore
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* differs in spirit from the above ffz (man ffs).
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*/
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extern inline unsigned long kernel_ffs(unsigned long w)
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{
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return w ? cris_swapwbrlz (w) + 1 : 0;
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}
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#endif
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