path: root/arch/arm/vfp/vfpsingle.c

/*
 *  linux/arch/arm/vfp/vfpsingle.c
 *
 * This code is derived in part from John R. Housers softfloat library, which
 * carries the following notice:
 *
 * ===========================================================================
 * This C source file is part of the SoftFloat IEC/IEEE Floating-point
 * Arithmetic Package, Release 2.
 *
 * Written by John R. Hauser.  This work was made possible in part by the
 * International Computer Science Institute, located at Suite 600, 1947 Center
 * Street, Berkeley, California 94704.  Funding was partially provided by the
 * National Science Foundation under grant MIP-9311980.  The original version
 * of this code was written as part of a project to build a fixed-point vector
 * processor in collaboration with the University of California at Berkeley,
 * overseen by Profs. Nelson Morgan and John Wawrzynek.  More information
 * is available through the web page `http://HTTP.CS.Berkeley.EDU/~jhauser/
 * arithmetic/softfloat.html'.
 *
 * THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE.  Although reasonable effort
 * has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT
 * TIMES RESULT IN INCORRECT BEHAVIOR.  USE OF THIS SOFTWARE IS RESTRICTED TO
 * PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY
 * AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE.
 *
 * Derivative works are acceptable, even for commercial purposes, so long as
 * (1) they include prominent notice that the work is derivative, and (2) they
 * include prominent notice akin to these three paragraphs for those parts of
 * this code that are retained.
 * ===========================================================================
 */
#include <linux/kernel.h>
#include <linux/bitops.h>

#include <asm/div64.h>
#include <asm/vfp.h>

#include "vfpinstr.h"
#include "vfp.h"

static struct vfp_single vfp_single_default_qnan = {
	.exponent	= 255,
	.sign		= 0,
	.significand	= VFP_SINGLE_SIGNIFICAND_QNAN,
};

static void vfp_single_dump(const char *str, struct vfp_single *s)
{
	pr_debug("VFP: %s: sign=%d exponent=%d significand=%08x\n",
		 str, s->sign != 0, s->exponent, s->significand);
}

static void vfp_single_normalise_denormal(struct vfp_single *vs)
{
	int bits = 31 - fls(vs->significand);

	vfp_single_dump("normalise_denormal: in", vs);

	if (bits) {
		vs->exponent -= bits - 1;
		vs->significand <<= bits;
	}

	vfp_single_dump("normalise_denormal: out", vs);
}

#ifndef DEBUG
#define vfp_single_normaliseround(sd,vsd,fpscr,except,func) __vfp_single_normaliseround(sd,vsd,fpscr,except)
u32 __vfp_single_normaliseround(int sd, struct vfp_single *vs, u32 fpscr, u32 exceptions)
#else
u32 vfp_single_normaliseround(int sd, struct vfp_single *vs, u32 fpscr, u32 exceptions, const char *func)
#endif
{
	u32 significand, incr, rmode;
	int exponent, shift, underflow;

	vfp_single_dump("pack: in", vs);

	/*
	 * Infinities and NaNs are a special case.
	 */
	if (vs->exponent == 255 && (vs->significand == 0 || exceptions))
		goto pack;

	/*
	 * Special-case zero.
	 */
	if (vs->significand == 0) {
		vs->exponent = 0;
		goto pack;
	}

	exponent = vs->exponent;
	significand = vs->significand;

	/*
	 * Normalise first.  Note that we shift the significand up to
	 * bit 31, so we have VFP_SINGLE_LOW_BITS + 1 below the least
	 * significant bit.
	 */
	shift = 32 - fls(significand);
	if (shift < 32 && shift) {
		exponent -= shift;
		significand <<= shift;
	}