s_truncf.s

glibc 2.9,最新版的C语言库函数

/* truncf function.  PowerPC32 version.
   Copyright (C) 2004, 2006 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, write to the Free
   Software Foundation, Inc., 1 Franklin Street, Fifth Floor, Boston MA
   02110-1301 USA.  */

#include <sysdep.h>

	.section	.rodata.cst4,"aM",@progbits,4
	.align	2
.LC0:	/* 2**23 */
	.long 0x4b000000

/* float [fp1] truncf (float x [fp1])
   IEEE 1003.1 trunc function.  IEEE specifies "trunc to the integer
   value, in floating format, nearest to but no larger in magnitude 
   then the argument."
   We set "round toward Zero" mode and trunc by adding +-2**23 then
   subtracting +-2**23.  */

	.section	".text"
ENTRY (__truncf)
	mffs	fp11		/* Save current FPU rounding mode.  */
#ifdef SHARED
	mflr	r11
	cfi_register(lr,r11)
# ifdef HAVE_ASM_PPC_REL16
	bcl	20,31,1f
1:	mflr	r9
	addis	r9,r9,.LC0-1b@ha
	lfs	fp13,.LC0-1b@l(r9)
# else
	bl	_GLOBAL_OFFSET_TABLE_@local-4
	mflr	r10
	lwz	r9,.LC0@got(10)
	lfs	fp13,0(r9)
# endif
	mtlr	r11
	cfi_same_value (lr)
#else
	lis	r9,.LC0@ha
	lfs	fp13,.LC0@l(r9)
#endif
	fabs	fp0,fp1
	fsubs	fp12,fp13,fp13	/* generate 0.0  */
	fcmpu	cr7,fp0,fp13	/* if (fabs(x) > TWO23)  */
	fcmpu	cr6,fp1,fp12	/* if (x > 0.0)  */
	bnllr-	cr7
	mtfsfi	7,1		/* Set rounding toward 0 mode.  */
	ble-	cr6,.L4
	fadds	fp1,fp1,fp13	/* x+= TWO23;  */
	fsubs	fp1,fp1,fp13	/* x-= TWO23;  */
	fabs	fp1,fp1		/* if (x == 0.0)  */
				/* x = 0.0; */
	mtfsf	0x01,fp11	/* restore previous rounding mode.  */
	blr
.L4:
	bge-	cr6,.L9		/* if (x < 0.0)  */
	fsubs	fp1,fp1,fp13	/* x-= TWO23;  */
	fadds	fp1,fp1,fp13	/* x+= TWO23;  */
	fnabs	fp1,fp1		/* if (x == 0.0)  */
				/* x = -0.0; */
.L9:
	mtfsf	0x01,fp11	/* restore previous rounding mode.  */
	blr
	END (__truncf)

weak_alias (__truncf, truncf)