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Initial revision

/*	$OpenBSD: fcnvxf.c,v 1.7 2003/04/10 17:27:58 mickey Exp $	*/
/*
  (c) Copyright 1986 HEWLETT-PACKARD COMPANY
  To anyone who acknowledges that this file is provided "AS IS"
  without any express or implied warranty:
      permission to use, copy, modify, and distribute this file
  for any purpose is hereby granted without fee, provided that
  the above copyright notice and this notice appears in all
  copies, and that the name of Hewlett-Packard Company not be
  used in advertising or publicity pertaining to distribution
  of the software without specific, written prior permission.
  Hewlett-Packard Company makes no representations about the
  suitability of this software for any purpose.
*/
/* @(#)fcnvxf.c: Revision: 2.7.88.1 Date: 93/12/07 15:06:16 */

#include "float.h"
#include "sgl_float.h"
#include "dbl_float.h"
#include "cnv_float.h"

/*
 *  Convert single fixed-point to single floating-point format
 */
int
sgl_to_sgl_fcnvxf(srcptr, null, dstptr, status)
	int *srcptr, *null;
	sgl_floating_point *dstptr;
	unsigned int *status;
{
	register int src, dst_exponent;
	register unsigned int result = 0;

	src = *srcptr;
	/*
	 * set sign bit of result and get magnitude of source
	 */
	if (src < 0) {
		Sgl_setone_sign(result);
		Int_negate(src);
	}
	else {
		Sgl_setzero_sign(result);
		/* Check for zero */
		if (src == 0) {
			Sgl_setzero(result);
			*dstptr = result;
			return(NOEXCEPTION);
		}
	}
	/*
	 * Generate exponent and normalized mantissa
	 */
	dst_exponent = 16;    /* initialize for normalization */
	/*
	 * Check word for most significant bit set.  Returns
	 * a value in dst_exponent indicating the bit position,
	 * between -1 and 30.
	 */
	Find_ms_one_bit(src,dst_exponent);
	/*  left justify source, with msb at bit position 1  */
	if (dst_exponent >= 0) src <<= dst_exponent;
	else src = 1 << 30;
	Sgl_set_mantissa(result, src >> (SGL_EXP_LENGTH-1));
	Sgl_set_exponent(result, 30+SGL_BIAS - dst_exponent);

	/* check for inexact */
	if (Int_isinexact_to_sgl(src)) {
		switch (Rounding_mode()) {
			case ROUNDPLUS:
				if (Sgl_iszero_sign(result))
					Sgl_increment(result);
				break;
			case ROUNDMINUS:
				if (Sgl_isone_sign(result))
					Sgl_increment(result);
				break;
			case ROUNDNEAREST:
				Sgl_roundnearest_from_int(src,result);
		}
		if (Is_inexacttrap_enabled()) {
			*dstptr = result;
			return(INEXACTEXCEPTION);
		}
		else Set_inexactflag();
	}
	*dstptr = result;
	return(NOEXCEPTION);
}

/*
 *  Single Fixed-point to Double Floating-point
 */
int
sgl_to_dbl_fcnvxf(srcptr, null, dstptr, status)
	int *srcptr, *null;
	dbl_floating_point *dstptr;
	unsigned int *status;
{
	register int src, dst_exponent;
	register unsigned int resultp1 = 0, resultp2 = 0;

	src = *srcptr;
	/*
	 * set sign bit of result and get magnitude of source
	 */
	if (src < 0) {
		Dbl_setone_sign(resultp1);
		Int_negate(src);
	}
	else {
		Dbl_setzero_sign(resultp1);
		/* Check for zero */
		if (src == 0) {
			Dbl_setzero(resultp1,resultp2);
			Dbl_copytoptr(resultp1,resultp2,dstptr);
			return(NOEXCEPTION);
		}
	}
	/*
	 * Generate exponent and normalized mantissa
	 */
	dst_exponent = 16;    /* initialize for normalization */
	/*
	 * Check word for most significant bit set.  Returns
	 * a value in dst_exponent indicating the bit position,
	 * between -1 and 30.
	 */
	Find_ms_one_bit(src,dst_exponent);
	/*  left justify source, with msb at bit position 1  */
	if (dst_exponent >= 0) src <<= dst_exponent;
	else src = 1 << 30;
	Dbl_set_mantissap1(resultp1, (src >> (DBL_EXP_LENGTH - 1)));
	Dbl_set_mantissap2(resultp2, (src << (33-DBL_EXP_LENGTH)));
	Dbl_set_exponent(resultp1, (30+DBL_BIAS) - dst_exponent);
	Dbl_copytoptr(resultp1,resultp2,dstptr);
	return(NOEXCEPTION);
}

/*
 *  Double Fixed-point to Single Floating-point
 */
int
dbl_to_sgl_fcnvxf(srcptr, null, dstptr, status)
	dbl_integer *srcptr, *null;
	sgl_floating_point *dstptr;
	unsigned int *status;
{
	int dst_exponent, srcp1;
	unsigned int result = 0, srcp2;

	Dint_copyfromptr(srcptr,srcp1,srcp2);
	/*
	 * set sign bit of result and get magnitude of source
	 */
	if (srcp1 < 0) {
		Sgl_setone_sign(result);
		Dint_negate(srcp1,srcp2);
	}
	else {
		Sgl_setzero_sign(result);
		/* Check for zero */
		if (srcp1 == 0 && srcp2 == 0) {
			Sgl_setzero(result);
			*dstptr = result;
			return(NOEXCEPTION);
		}
	}
	/*
	 * Generate exponent and normalized mantissa
	 */
	dst_exponent = 16;    /* initialize for normalization */
	if (srcp1 == 0) {
		/*
		 * Check word for most significant bit set.  Returns
		 * a value in dst_exponent indicating the bit position,
		 * between -1 and 30.
		 */
		Find_ms_one_bit(srcp2,dst_exponent);
		/*  left justify source, with msb at bit position 1  */
		if (dst_exponent >= 0) {
			srcp1 = srcp2 << dst_exponent;
			srcp2 = 0;
		}
		else {
			srcp1 = srcp2 >> 1;
			srcp2 <<= 31;
		}
		/*
		 *  since msb set is in second word, need to
		 *  adjust bit position count
		 */
		dst_exponent += 32;
	}
	else {
		/*
		 * Check word for most significant bit set.  Returns
		 * a value in dst_exponent indicating the bit position,
		 * between -1 and 30.
		 *
		 */
		Find_ms_one_bit(srcp1,dst_exponent);
		/*  left justify source, with msb at bit position 1  */
		if (dst_exponent > 0) {
			Variable_shift_double(srcp1,srcp2,(32-dst_exponent),
			 srcp1);
			srcp2 <<= dst_exponent;
		}
		/*
		 * If dst_exponent = 0, we don't need to shift anything.
		 * If dst_exponent = -1, src = - 2**63 so we won't need to
		 * shift srcp2.
		 */
		else srcp1 >>= -(dst_exponent);
	}
	Sgl_set_mantissa(result, (srcp1 >> (SGL_EXP_LENGTH - 1)));
	Sgl_set_exponent(result, (62+SGL_BIAS) - dst_exponent);

	/* check for inexact */
	if (Dint_isinexact_to_sgl(srcp1,srcp2)) {
		switch (Rounding_mode()) {
			case ROUNDPLUS:
				if (Sgl_iszero_sign(result))
					Sgl_increment(result);
				break;
			case ROUNDMINUS:
				if (Sgl_isone_sign(result))
					Sgl_increment(result);
				break;
			case ROUNDNEAREST:
				Sgl_roundnearest_from_dint(srcp1,srcp2,result);
		}
		if (Is_inexacttrap_enabled()) {
			*dstptr = result;
			return(INEXACTEXCEPTION);
		}
		else Set_inexactflag();
	}
	*dstptr = result;
	return(NOEXCEPTION);
}

/*
 *  Double Fixed-point to Double Floating-point
 */
int
dbl_to_dbl_fcnvxf(srcptr, null, dstptr, status)
	dbl_integer *srcptr, *null;
	dbl_floating_point *dstptr;
	unsigned int *status;
{
	register int srcp1, dst_exponent;
	register unsigned int srcp2, resultp1 = 0, resultp2 = 0;

	Dint_copyfromptr(srcptr,srcp1,srcp2);
	/*
	 * set sign bit of result and get magnitude of source
	 */
	if (srcp1 < 0) {
		Dbl_setone_sign(resultp1);
		Dint_negate(srcp1,srcp2);
	}
	else {
		Dbl_setzero_sign(resultp1);
		/* Check for zero */
		if (srcp1 == 0 && srcp2 ==0) {
			Dbl_setzero(resultp1,resultp2);
			Dbl_copytoptr(resultp1,resultp2,dstptr);
			return(NOEXCEPTION);
		}
	}
	/*
	 * Generate exponent and normalized mantissa
	 */
	dst_exponent = 16;    /* initialize for normalization */
	if (srcp1 == 0) {
		/*
		 * Check word for most significant bit set.  Returns
		 * a value in dst_exponent indicating the bit position,
		 * between -1 and 30.
		 */
		Find_ms_one_bit(srcp2,dst_exponent);
		/*  left justify source, with msb at bit position 1  */
		if (dst_exponent >= 0) {
			srcp1 = srcp2 << dst_exponent;
			srcp2 = 0;
		}
		else {
			srcp1 = srcp2 >> 1;
			srcp2 <<= 31;
		}
		/*
		 *  since msb set is in second word, need to
		 *  adjust bit position count
		 */
		dst_exponent += 32;
	}
	else {
		/*
		 * Check word for most significant bit set.  Returns
		 * a value in dst_exponent indicating the bit position,
		 * between -1 and 30.
		 */
		Find_ms_one_bit(srcp1,dst_exponent);
		/*  left justify source, with msb at bit position 1  */
		if (dst_exponent > 0) {
			Variable_shift_double(srcp1,srcp2,(32-dst_exponent),
			 srcp1);
			srcp2 <<= dst_exponent;
		}
		/*
		 * If dst_exponent = 0, we don't need to shift anything.
		 * If dst_exponent = -1, src = - 2**63 so we won't need to
		 * shift srcp2.
		 */
		else srcp1 >>= -(dst_exponent);
	}
	Dbl_set_mantissap1(resultp1, srcp1 >> (DBL_EXP_LENGTH-1));
	Shiftdouble(srcp1,srcp2,DBL_EXP_LENGTH-1,resultp2);
	Dbl_set_exponent(resultp1, (62+DBL_BIAS) - dst_exponent);

	/* check for inexact */
	if (Dint_isinexact_to_dbl(srcp2)) {
		switch (Rounding_mode()) {
			case ROUNDPLUS:
				if (Dbl_iszero_sign(resultp1)) {
					Dbl_increment(resultp1,resultp2);
				}
				break;
			case ROUNDMINUS:
				if (Dbl_isone_sign(resultp1)) {
					Dbl_increment(resultp1,resultp2);
				}
				break;
			case ROUNDNEAREST:
				Dbl_roundnearest_from_dint(srcp2,resultp1,
				resultp2);
		}
		if (Is_inexacttrap_enabled()) {
			Dbl_copytoptr(resultp1,resultp2,dstptr);
			return(INEXACTEXCEPTION);
		}
		else Set_inexactflag();
	}
	Dbl_copytoptr(resultp1,resultp2,dstptr);
	return(NOEXCEPTION);
}