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Commit aacf29bf authored by David Howells's avatar David Howells Committed by Rusty Russell
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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: default avatarDavid 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: default avatarRusty Russell <rusty@rustcorp.com.au>
parent cf7f601c

include/asm-generic/bitops/count_zeros.h

0 → 100644
+57 −0
Original line number Diff line number Diff line 
/* Count leading and trailing zeros functions

 *

 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.

 * Written by David Howells (dhowells@redhat.com)

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public Licence

 * as published by the Free Software Foundation; either version

 * 2 of the Licence, or (at your option) any later version.

 */



#ifndef _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_

#define _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_



#include <asm/bitops.h>



/**

 * count_leading_zeros - Count the number of zeros from the MSB back

 * @x: The value

 *

 * Count the number of leading zeros from the MSB going towards the LSB in @x.

 *

 * If the MSB of @x is set, the result is 0.

 * If only the LSB of @x is set, then the result is BITS_PER_LONG-1.

 * If @x is 0 then the result is COUNT_LEADING_ZEROS_0.

 */

static inline int count_leading_zeros(unsigned long x)

{

	if (sizeof(x) == 4)

		return BITS_PER_LONG - fls(x);

	else

		return BITS_PER_LONG - fls64(x);

}



#define COUNT_LEADING_ZEROS_0 BITS_PER_LONG



/**

 * count_trailing_zeros - Count the number of zeros from the LSB forwards

 * @x: The value

 *

 * Count the number of trailing zeros from the LSB going towards the MSB in @x.

 *

 * If the LSB of @x is set, the result is 0.

 * If only the MSB of @x is set, then the result is BITS_PER_LONG-1.

 * If @x is 0 then the result is COUNT_TRAILING_ZEROS_0.

 */

static inline int count_trailing_zeros(unsigned long x)

{

#define COUNT_TRAILING_ZEROS_0 (-1)



	if (sizeof(x) == 4)

		return ffs(x);

	else

		return (x != 0) ? __ffs(x) : COUNT_TRAILING_ZEROS_0;

}



#endif /* _ASM_GENERIC_BITOPS_COUNT_ZEROS_H_ */

lib/mpi/longlong.h

+2 −136
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ 
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,

 * MA 02111-1307, USA. */



#include <asm-generic/bitops/count_zeros.h>



/* You have to define the following before including this file:

 *

 * UWtype -- An unsigned type, default type for operations (typically a "word")
@@ -146,12 +148,6 @@ do { \ 
	: "1" ((USItype)(n1)), \

		"r" ((USItype)(n0)), \

		"r" ((USItype)(d)))



#define count_leading_zeros(count, x) \

	__asm__ ("clz %0,%1" \

	: "=r" ((USItype)(count)) \

	: "r" ((USItype)(x)))

#define COUNT_LEADING_ZEROS_0 32

#endif /* __a29k__ */



#if defined(__alpha) && W_TYPE_SIZE == 64
@@ -298,11 +294,6 @@ extern UDItype __udiv_qrnnd(); 
	: "1" ((USItype)(nh)), \

		"0" ((USItype)(nl)), \

		"g" ((USItype)(d)))

#define count_leading_zeros(count, x) \

	__asm__ ("bsch/1 %1,%0" \

	: "=g" (count) \

	: "g" ((USItype)(x)), \

	     "0" ((USItype)0))

#endif



/***************************************
@@ -354,27 +345,6 @@ do { USItype __r; \ 
} while (0)

extern USItype __udiv_qrnnd();

#endif /* LONGLONG_STANDALONE */

#define count_leading_zeros(count, x) \

do { \

	USItype __tmp; \

	__asm__ ( \

	"ldi             1,%0\n" \

	"extru,=	%1,15,16,%%r0  ; Bits 31..16 zero?\n" \

	"extru,tr	%1,15,16,%1    ; No.  Shift down, skip add.\n" \

	"ldo		16(%0),%0      ; Yes.	Perform add.\n" \

	"extru,=	%1,23,8,%%r0   ; Bits 15..8 zero?\n" \

	"extru,tr	%1,23,8,%1     ; No.  Shift down, skip add.\n" \

	"ldo		8(%0),%0       ; Yes.	Perform add.\n" \

	"extru,=	%1,27,4,%%r0   ; Bits 7..4 zero?\n" \

	"extru,tr	%1,27,4,%1     ; No.  Shift down, skip add.\n" \

	"ldo		4(%0),%0       ; Yes.	Perform add.\n" \

	"extru,=	%1,29,2,%%r0   ; Bits 3..2 zero?\n" \

	"extru,tr	%1,29,2,%1     ; No.  Shift down, skip add.\n" \

	"ldo		2(%0),%0       ; Yes.	Perform add.\n" \

	"extru		%1,30,1,%1     ; Extract bit 1.\n" \

	"sub		%0,%1,%0       ; Subtract it.              " \

	: "=r" (count), "=r" (__tmp) : "1" (x)); \

} while (0)

#endif /* hppa */



/***************************************
@@ -457,15 +427,6 @@ do { \ 
	: "0" ((USItype)(n0)), \

	     "1" ((USItype)(n1)), \

	     "rm" ((USItype)(d)))

#define count_leading_zeros(count, x) \

do { \

	USItype __cbtmp; \

	__asm__ ("bsrl %1,%0" \

	: "=r" (__cbtmp) : "rm" ((USItype)(x))); \

	(count) = __cbtmp ^ 31; \

} while (0)

#define count_trailing_zeros(count, x) \

	__asm__ ("bsfl %1,%0" : "=r" (count) : "rm" ((USItype)(x)))

#ifndef UMUL_TIME

#define UMUL_TIME 40

#endif
@@ -536,15 +497,6 @@ do { \ 
	     "dI" ((USItype)(d))); \

	(r) = __rq.__i.__l; (q) = __rq.__i.__h; \

} while (0)

#define count_leading_zeros(count, x) \

do { \

	USItype __cbtmp; \

	__asm__ ("scanbit %1,%0" \

	: "=r" (__cbtmp) \

	: "r" ((USItype)(x))); \

	(count) = __cbtmp ^ 31; \

} while (0)

#define COUNT_LEADING_ZEROS_0 (-32)	/* sic */

#if defined(__i960mx)		/* what is the proper symbol to test??? */

#define rshift_rhlc(r, h, l, c) \

do { \
@@ -603,11 +555,6 @@ do { \ 
	: "0" ((USItype)(n0)), \

	     "1" ((USItype)(n1)), \

	     "dmi" ((USItype)(d)))

#define count_leading_zeros(count, x) \

	__asm__ ("bfffo %1{%b2:%b2},%0" \

	: "=d" ((USItype)(count)) \

	: "od" ((USItype)(x)), "n" (0))

#define COUNT_LEADING_ZEROS_0 32

#else /* not mc68020 */

#define umul_ppmm(xh, xl, a, b) \

do { USItype __umul_tmp1, __umul_tmp2; \
@@ -664,15 +611,6 @@ do { USItype __umul_tmp1, __umul_tmp2; \ 
	     "rJ" ((USItype)(bh)), \

	     "rJ" ((USItype)(al)), \

	     "rJ" ((USItype)(bl)))

#define count_leading_zeros(count, x) \

do { \

	USItype __cbtmp; \

	__asm__ ("ff1 %0,%1" \

	: "=r" (__cbtmp) \

	: "r" ((USItype)(x))); \

	(count) = __cbtmp ^ 31; \

} while (0)

#define COUNT_LEADING_ZEROS_0 63	/* sic */

#if defined(__m88110__)

#define umul_ppmm(wh, wl, u, v) \

do { \
@@ -779,12 +717,6 @@ do { \ 
	: "0" (__xx.__ll), \

	     "g" ((USItype)(d))); \

	(r) = __xx.__i.__l; (q) = __xx.__i.__h; })

#define count_trailing_zeros(count, x) \

do { \

	__asm__("ffsd      %2,%0" \

	: "=r"((USItype) (count)) \

	: "0"((USItype) 0), "r"((USItype) (x))); \

	} while (0)

#endif /* __ns32000__ */



/***************************************
@@ -855,11 +787,6 @@ do { \ 
		"rI" ((USItype)(al)), \

		"r" ((USItype)(bl))); \

} while (0)

#define count_leading_zeros(count, x) \

	__asm__ ("{cntlz|cntlzw} %0,%1" \

	: "=r" ((USItype)(count)) \

	: "r" ((USItype)(x)))

#define COUNT_LEADING_ZEROS_0 32

#if defined(_ARCH_PPC)

#define umul_ppmm(ph, pl, m0, m1) \

do { \
@@ -1001,19 +928,6 @@ do { \ 
} while (0)

#define UMUL_TIME 20

#define UDIV_TIME 200

#define count_leading_zeros(count, x) \

do { \

	if ((x) >= 0x10000) \

		__asm__ ("clz     %0,%1" \

		: "=r" ((USItype)(count)) \

		: "r" ((USItype)(x) >> 16)); \

	else { \

		__asm__ ("clz   %0,%1" \

		: "=r" ((USItype)(count)) \

		: "r" ((USItype)(x))); \

		(count) += 16; \

	} \

} while (0)

#endif /* RT/ROMP */



/***************************************
@@ -1142,13 +1056,6 @@ do { \ 
	"rI" ((USItype)(d)) \

	: "%g1" __AND_CLOBBER_CC)

#define UDIV_TIME 37

#define count_leading_zeros(count, x) \

	__asm__ ("scan %1,0,%0" \

	: "=r" ((USItype)(x)) \

	: "r" ((USItype)(count)))

/* Early sparclites return 63 for an argument of 0, but they warn that future

	implementations might change this.  Therefore, leave COUNT_LEADING_ZEROS_0

	undefined.  */

#endif /* __sparclite__ */

#endif /* __sparc_v8__ */

	/* Default to sparc v7 versions of umul_ppmm and udiv_qrnnd.  */
@@ -1454,47 +1361,6 @@ do { \ 
#define udiv_qrnnd __udiv_qrnnd_c

#endif



#undef count_leading_zeros

#if !defined(count_leading_zeros)

	extern

#ifdef __STDC__

			const

#endif

			unsigned char __clz_tab[];

#define count_leading_zeros(count, x) \

do { \

	UWtype __xr = (x); \

	UWtype __a; \

	\

	if (W_TYPE_SIZE <= 32) { \

		__a = __xr < ((UWtype) 1 << 2*__BITS4) \

		? (__xr < ((UWtype) 1 << __BITS4) ? 0 : __BITS4) \

		: (__xr < ((UWtype) 1 << 3*__BITS4) ?  2*__BITS4 : 3*__BITS4); \

	} \

	else { \

		for (__a = W_TYPE_SIZE - 8; __a > 0; __a -= 8) \

			if (((__xr >> __a) & 0xff) != 0) \

				break; \

	} \

	\

	(count) = W_TYPE_SIZE - (__clz_tab[__xr >> __a] + __a); \

} while (0)

	/* This version gives a well-defined value for zero. */

#define COUNT_LEADING_ZEROS_0 W_TYPE_SIZE

#endif



#if !defined(count_trailing_zeros)

/* Define count_trailing_zeros using count_leading_zeros.  The latter might be

	defined in asm, but if it is not, the C version above is good enough.  */

#define count_trailing_zeros(count, x) \

do { \

	UWtype __ctz_x = (x); \

	UWtype __ctz_c; \

	count_leading_zeros(__ctz_c, __ctz_x & -__ctz_x); \

	(count) = W_TYPE_SIZE - 1 - __ctz_c; \

} while (0)

#endif



#ifndef UDIV_NEEDS_NORMALIZATION

#define UDIV_NEEDS_NORMALIZATION 0

#endif

lib/mpi/mpi-bit.c

+1 −1
Original line number Diff line number Diff line
@@ -45,7 +45,7 @@ unsigned mpi_get_nbits(MPI a) 
	if (a->nlimbs) {

		mpi_limb_t alimb = a->d[a->nlimbs - 1];

		if (alimb)

			count_leading_zeros(n, alimb);

			n = count_leading_zeros(alimb);

		else

			n = BITS_PER_MPI_LIMB;

		n = BITS_PER_MPI_LIMB - n + (a->nlimbs - 1) * BITS_PER_MPI_LIMB;

lib/mpi/mpi-pow.c

+2 −2
Original line number Diff line number Diff line
@@ -77,7 +77,7 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod) 
	mp = mp_marker = mpi_alloc_limb_space(msize);

	if (!mp)

		goto enomem;

	count_leading_zeros(mod_shift_cnt, mod->d[msize - 1]);

	mod_shift_cnt = count_leading_zeros(mod->d[msize - 1]);

	if (mod_shift_cnt)

		mpihelp_lshift(mp, mod->d, msize, mod_shift_cnt);

	else
@@ -169,7 +169,7 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod) 


		i = esize - 1;

		e = ep[i];

		count_leading_zeros(c, e);

		c = count_leading_zeros(e);

		e = (e << c) << 1;	/* shift the exp bits to the left, lose msb */

		c = BITS_PER_MPI_LIMB - 1 - c;