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MPILIB: Provide count_leading/trailing_zeros() based on arch functions
Provide count_leading/trailing_zeros() macros based on extant arch bit scanning functions rather than reimplementing from scratch in MPILIB. Whilst we're at it, turn count_foo_zeros(n, x) into n = count_foo_zeros(x). Also move the definition to asm-generic as other people may be interested in using it. Signed-off-by: David Howells <dhowells@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Dmitry Kasatkin <dmitry.kasatkin@intel.com> Cc: Arnd Bergmann <arnd@arndb.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
David Howells
Rusty Russell
parent
cf7f601c06
commit
aacf29bf1b
57
include/asm-generic/bitops/count_zeros.h
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57
include/asm-generic/bitops/count_zeros.h
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@ -0,0 +1,57 @@
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/* Count leading and trailing zeros functions
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*
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* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#ifndef _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_
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#define _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_
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#include <asm/bitops.h>
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/**
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* count_leading_zeros - Count the number of zeros from the MSB back
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* @x: The value
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*
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* Count the number of leading zeros from the MSB going towards the LSB in @x.
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*
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* If the MSB of @x is set, the result is 0.
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* If only the LSB of @x is set, then the result is BITS_PER_LONG-1.
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* If @x is 0 then the result is COUNT_LEADING_ZEROS_0.
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*/
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static inline int count_leading_zeros(unsigned long x)
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{
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if (sizeof(x) == 4)
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return BITS_PER_LONG - fls(x);
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else
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return BITS_PER_LONG - fls64(x);
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}
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#define COUNT_LEADING_ZEROS_0 BITS_PER_LONG
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/**
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* count_trailing_zeros - Count the number of zeros from the LSB forwards
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* @x: The value
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*
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* Count the number of trailing zeros from the LSB going towards the MSB in @x.
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*
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* If the LSB of @x is set, the result is 0.
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* If only the MSB of @x is set, then the result is BITS_PER_LONG-1.
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* If @x is 0 then the result is COUNT_TRAILING_ZEROS_0.
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*/
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static inline int count_trailing_zeros(unsigned long x)
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{
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#define COUNT_TRAILING_ZEROS_0 (-1)
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if (sizeof(x) == 4)
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return ffs(x);
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else
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return (x != 0) ? __ffs(x) : COUNT_TRAILING_ZEROS_0;
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}
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#endif /* _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_ */
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@ -19,6 +19,8 @@
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* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
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* MA 02111-1307, USA. */
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#include <asm-generic/bitops/count_zeros.h>
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/* You have to define the following before including this file:
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*
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* UWtype -- An unsigned type, default type for operations (typically a "word")
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@ -146,12 +148,6 @@ do { \
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: "1" ((USItype)(n1)), \
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"r" ((USItype)(n0)), \
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"r" ((USItype)(d)))
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#define count_leading_zeros(count, x) \
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__asm__ ("clz %0,%1" \
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: "=r" ((USItype)(count)) \
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: "r" ((USItype)(x)))
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#define COUNT_LEADING_ZEROS_0 32
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#endif /* __a29k__ */
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#if defined(__alpha) && W_TYPE_SIZE == 64
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@ -298,11 +294,6 @@ extern UDItype __udiv_qrnnd();
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: "1" ((USItype)(nh)), \
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"0" ((USItype)(nl)), \
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"g" ((USItype)(d)))
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#define count_leading_zeros(count, x) \
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__asm__ ("bsch/1 %1,%0" \
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: "=g" (count) \
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: "g" ((USItype)(x)), \
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"0" ((USItype)0))
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#endif
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/***************************************
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@ -354,27 +345,6 @@ do { USItype __r; \
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} while (0)
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extern USItype __udiv_qrnnd();
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#endif /* LONGLONG_STANDALONE */
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#define count_leading_zeros(count, x) \
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do { \
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USItype __tmp; \
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__asm__ ( \
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"ldi 1,%0\n" \
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"extru,= %1,15,16,%%r0 ; Bits 31..16 zero?\n" \
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"extru,tr %1,15,16,%1 ; No. Shift down, skip add.\n" \
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"ldo 16(%0),%0 ; Yes. Perform add.\n" \
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"extru,= %1,23,8,%%r0 ; Bits 15..8 zero?\n" \
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"extru,tr %1,23,8,%1 ; No. Shift down, skip add.\n" \
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"ldo 8(%0),%0 ; Yes. Perform add.\n" \
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"extru,= %1,27,4,%%r0 ; Bits 7..4 zero?\n" \
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"extru,tr %1,27,4,%1 ; No. Shift down, skip add.\n" \
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"ldo 4(%0),%0 ; Yes. Perform add.\n" \
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"extru,= %1,29,2,%%r0 ; Bits 3..2 zero?\n" \
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"extru,tr %1,29,2,%1 ; No. Shift down, skip add.\n" \
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"ldo 2(%0),%0 ; Yes. Perform add.\n" \
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"extru %1,30,1,%1 ; Extract bit 1.\n" \
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"sub %0,%1,%0 ; Subtract it. " \
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: "=r" (count), "=r" (__tmp) : "1" (x)); \
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} while (0)
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#endif /* hppa */
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/***************************************
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@ -457,15 +427,6 @@ do { \
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: "0" ((USItype)(n0)), \
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"1" ((USItype)(n1)), \
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"rm" ((USItype)(d)))
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#define count_leading_zeros(count, x) \
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do { \
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USItype __cbtmp; \
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__asm__ ("bsrl %1,%0" \
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: "=r" (__cbtmp) : "rm" ((USItype)(x))); \
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(count) = __cbtmp ^ 31; \
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} while (0)
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#define count_trailing_zeros(count, x) \
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__asm__ ("bsfl %1,%0" : "=r" (count) : "rm" ((USItype)(x)))
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#ifndef UMUL_TIME
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#define UMUL_TIME 40
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#endif
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@ -536,15 +497,6 @@ do { \
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"dI" ((USItype)(d))); \
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(r) = __rq.__i.__l; (q) = __rq.__i.__h; \
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} while (0)
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#define count_leading_zeros(count, x) \
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do { \
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USItype __cbtmp; \
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__asm__ ("scanbit %1,%0" \
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: "=r" (__cbtmp) \
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: "r" ((USItype)(x))); \
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(count) = __cbtmp ^ 31; \
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} while (0)
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#define COUNT_LEADING_ZEROS_0 (-32) /* sic */
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#if defined(__i960mx) /* what is the proper symbol to test??? */
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#define rshift_rhlc(r, h, l, c) \
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do { \
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@ -603,11 +555,6 @@ do { \
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: "0" ((USItype)(n0)), \
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"1" ((USItype)(n1)), \
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"dmi" ((USItype)(d)))
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#define count_leading_zeros(count, x) \
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__asm__ ("bfffo %1{%b2:%b2},%0" \
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: "=d" ((USItype)(count)) \
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: "od" ((USItype)(x)), "n" (0))
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#define COUNT_LEADING_ZEROS_0 32
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#else /* not mc68020 */
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#define umul_ppmm(xh, xl, a, b) \
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do { USItype __umul_tmp1, __umul_tmp2; \
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@ -664,15 +611,6 @@ do { USItype __umul_tmp1, __umul_tmp2; \
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"rJ" ((USItype)(bh)), \
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"rJ" ((USItype)(al)), \
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"rJ" ((USItype)(bl)))
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#define count_leading_zeros(count, x) \
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do { \
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USItype __cbtmp; \
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__asm__ ("ff1 %0,%1" \
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: "=r" (__cbtmp) \
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: "r" ((USItype)(x))); \
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(count) = __cbtmp ^ 31; \
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} while (0)
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#define COUNT_LEADING_ZEROS_0 63 /* sic */
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#if defined(__m88110__)
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#define umul_ppmm(wh, wl, u, v) \
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do { \
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@ -779,12 +717,6 @@ do { \
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: "0" (__xx.__ll), \
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"g" ((USItype)(d))); \
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(r) = __xx.__i.__l; (q) = __xx.__i.__h; })
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#define count_trailing_zeros(count, x) \
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do { \
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__asm__("ffsd %2,%0" \
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: "=r"((USItype) (count)) \
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: "0"((USItype) 0), "r"((USItype) (x))); \
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} while (0)
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#endif /* __ns32000__ */
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/***************************************
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@ -855,11 +787,6 @@ do { \
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"rI" ((USItype)(al)), \
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"r" ((USItype)(bl))); \
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} while (0)
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#define count_leading_zeros(count, x) \
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__asm__ ("{cntlz|cntlzw} %0,%1" \
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: "=r" ((USItype)(count)) \
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: "r" ((USItype)(x)))
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#define COUNT_LEADING_ZEROS_0 32
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#if defined(_ARCH_PPC)
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#define umul_ppmm(ph, pl, m0, m1) \
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do { \
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@ -1001,19 +928,6 @@ do { \
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} while (0)
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#define UMUL_TIME 20
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#define UDIV_TIME 200
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#define count_leading_zeros(count, x) \
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do { \
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if ((x) >= 0x10000) \
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__asm__ ("clz %0,%1" \
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: "=r" ((USItype)(count)) \
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: "r" ((USItype)(x) >> 16)); \
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else { \
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__asm__ ("clz %0,%1" \
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: "=r" ((USItype)(count)) \
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: "r" ((USItype)(x))); \
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(count) += 16; \
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} \
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} while (0)
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#endif /* RT/ROMP */
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/***************************************
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@ -1142,13 +1056,6 @@ do { \
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"rI" ((USItype)(d)) \
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: "%g1" __AND_CLOBBER_CC)
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#define UDIV_TIME 37
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#define count_leading_zeros(count, x) \
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__asm__ ("scan %1,0,%0" \
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: "=r" ((USItype)(x)) \
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: "r" ((USItype)(count)))
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/* Early sparclites return 63 for an argument of 0, but they warn that future
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implementations might change this. Therefore, leave COUNT_LEADING_ZEROS_0
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undefined. */
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#endif /* __sparclite__ */
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#endif /* __sparc_v8__ */
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/* Default to sparc v7 versions of umul_ppmm and udiv_qrnnd. */
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@ -1454,47 +1361,6 @@ do { \
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#define udiv_qrnnd __udiv_qrnnd_c
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#endif
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#undef count_leading_zeros
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#if !defined(count_leading_zeros)
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extern
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#ifdef __STDC__
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const
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#endif
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unsigned char __clz_tab[];
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#define count_leading_zeros(count, x) \
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do { \
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UWtype __xr = (x); \
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UWtype __a; \
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\
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if (W_TYPE_SIZE <= 32) { \
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__a = __xr < ((UWtype) 1 << 2*__BITS4) \
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? (__xr < ((UWtype) 1 << __BITS4) ? 0 : __BITS4) \
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: (__xr < ((UWtype) 1 << 3*__BITS4) ? 2*__BITS4 : 3*__BITS4); \
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} \
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else { \
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for (__a = W_TYPE_SIZE - 8; __a > 0; __a -= 8) \
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if (((__xr >> __a) & 0xff) != 0) \
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break; \
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} \
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\
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(count) = W_TYPE_SIZE - (__clz_tab[__xr >> __a] + __a); \
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} while (0)
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/* This version gives a well-defined value for zero. */
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#define COUNT_LEADING_ZEROS_0 W_TYPE_SIZE
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#endif
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#if !defined(count_trailing_zeros)
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/* Define count_trailing_zeros using count_leading_zeros. The latter might be
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defined in asm, but if it is not, the C version above is good enough. */
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#define count_trailing_zeros(count, x) \
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do { \
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UWtype __ctz_x = (x); \
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UWtype __ctz_c; \
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count_leading_zeros(__ctz_c, __ctz_x & -__ctz_x); \
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(count) = W_TYPE_SIZE - 1 - __ctz_c; \
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} while (0)
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#endif
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#ifndef UDIV_NEEDS_NORMALIZATION
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#define UDIV_NEEDS_NORMALIZATION 0
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#endif
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@ -45,7 +45,7 @@ unsigned mpi_get_nbits(MPI a)
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if (a->nlimbs) {
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mpi_limb_t alimb = a->d[a->nlimbs - 1];
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if (alimb)
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count_leading_zeros(n, alimb);
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n = count_leading_zeros(alimb);
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else
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n = BITS_PER_MPI_LIMB;
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n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB;
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@ -77,7 +77,7 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod)
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mp = mp_marker = mpi_alloc_limb_space(msize);
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if (!mp)
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goto enomem;
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count_leading_zeros(mod_shift_cnt, mod->d[msize - 1]);
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mod_shift_cnt = count_leading_zeros(mod->d[msize - 1]);
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if (mod_shift_cnt)
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mpihelp_lshift(mp, mod->d, msize, mod_shift_cnt);
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else
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@ -169,7 +169,7 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod)
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i = esize - 1;
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e = ep[i];
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count_leading_zeros(c, e);
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c = count_leading_zeros(e);
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e = (e << c) << 1; /* shift the exp bits to the left, lose msb */
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c = BITS_PER_MPI_LIMB - 1 - c;
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