mirror of https://gitee.com/openkylin/linux.git
374 lines
9.0 KiB
C
374 lines
9.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Linux/PA-RISC Project (http://www.parisc-linux.org/)
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*
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* Floating-point emulation code
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* Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
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*/
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/*
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* BEGIN_DESC
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*
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* File:
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* @(#) pa/spmath/fcnvxf.c $Revision: 1.1 $
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*
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* Purpose:
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* Single Fixed-point to Single Floating-point
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* Single Fixed-point to Double Floating-point
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* Double Fixed-point to Single Floating-point
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* Double Fixed-point to Double Floating-point
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*
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* External Interfaces:
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* dbl_to_dbl_fcnvxf(srcptr,nullptr,dstptr,status)
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* dbl_to_sgl_fcnvxf(srcptr,nullptr,dstptr,status)
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* sgl_to_dbl_fcnvxf(srcptr,nullptr,dstptr,status)
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* sgl_to_sgl_fcnvxf(srcptr,nullptr,dstptr,status)
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*
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* Internal Interfaces:
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*
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* Theory:
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* <<please update with a overview of the operation of this file>>
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*
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* END_DESC
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*/
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#include "float.h"
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#include "sgl_float.h"
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#include "dbl_float.h"
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#include "cnv_float.h"
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/*
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* Convert single fixed-point to single floating-point format
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*/
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int
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sgl_to_sgl_fcnvxf(
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int *srcptr,
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unsigned int *nullptr,
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sgl_floating_point *dstptr,
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unsigned int *status)
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{
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register int src, dst_exponent;
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register unsigned int result = 0;
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src = *srcptr;
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/*
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* set sign bit of result and get magnitude of source
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*/
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if (src < 0) {
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Sgl_setone_sign(result);
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Int_negate(src);
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}
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else {
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Sgl_setzero_sign(result);
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/* Check for zero */
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if (src == 0) {
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Sgl_setzero(result);
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*dstptr = result;
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return(NOEXCEPTION);
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}
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}
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/*
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* Generate exponent and normalized mantissa
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*/
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dst_exponent = 16; /* initialize for normalization */
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/*
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* Check word for most significant bit set. Returns
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* a value in dst_exponent indicating the bit position,
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* between -1 and 30.
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*/
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Find_ms_one_bit(src,dst_exponent);
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/* left justify source, with msb at bit position 1 */
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if (dst_exponent >= 0) src <<= dst_exponent;
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else src = 1 << 30;
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Sgl_set_mantissa(result, src >> (SGL_EXP_LENGTH-1));
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Sgl_set_exponent(result, 30+SGL_BIAS - dst_exponent);
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/* check for inexact */
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if (Int_isinexact_to_sgl(src)) {
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switch (Rounding_mode()) {
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case ROUNDPLUS:
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if (Sgl_iszero_sign(result))
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Sgl_increment(result);
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break;
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case ROUNDMINUS:
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if (Sgl_isone_sign(result))
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Sgl_increment(result);
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break;
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case ROUNDNEAREST:
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Sgl_roundnearest_from_int(src,result);
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}
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if (Is_inexacttrap_enabled()) {
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*dstptr = result;
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return(INEXACTEXCEPTION);
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}
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else Set_inexactflag();
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}
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*dstptr = result;
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return(NOEXCEPTION);
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}
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/*
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* Single Fixed-point to Double Floating-point
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*/
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int
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sgl_to_dbl_fcnvxf(
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int *srcptr,
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unsigned int *nullptr,
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dbl_floating_point *dstptr,
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unsigned int *status)
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{
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register int src, dst_exponent;
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register unsigned int resultp1 = 0, resultp2 = 0;
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src = *srcptr;
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/*
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* set sign bit of result and get magnitude of source
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*/
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if (src < 0) {
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Dbl_setone_sign(resultp1);
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Int_negate(src);
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}
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else {
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Dbl_setzero_sign(resultp1);
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/* Check for zero */
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if (src == 0) {
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Dbl_setzero(resultp1,resultp2);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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}
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/*
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* Generate exponent and normalized mantissa
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*/
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dst_exponent = 16; /* initialize for normalization */
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/*
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* Check word for most significant bit set. Returns
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* a value in dst_exponent indicating the bit position,
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* between -1 and 30.
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*/
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Find_ms_one_bit(src,dst_exponent);
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/* left justify source, with msb at bit position 1 */
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if (dst_exponent >= 0) src <<= dst_exponent;
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else src = 1 << 30;
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Dbl_set_mantissap1(resultp1, src >> DBL_EXP_LENGTH - 1);
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Dbl_set_mantissap2(resultp2, src << (33-DBL_EXP_LENGTH));
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Dbl_set_exponent(resultp1, (30+DBL_BIAS) - dst_exponent);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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/*
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* Double Fixed-point to Single Floating-point
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*/
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int
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dbl_to_sgl_fcnvxf(
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dbl_integer *srcptr,
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unsigned int *nullptr,
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sgl_floating_point *dstptr,
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unsigned int *status)
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{
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int dst_exponent, srcp1;
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unsigned int result = 0, srcp2;
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Dint_copyfromptr(srcptr,srcp1,srcp2);
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/*
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* set sign bit of result and get magnitude of source
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*/
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if (srcp1 < 0) {
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Sgl_setone_sign(result);
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Dint_negate(srcp1,srcp2);
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}
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else {
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Sgl_setzero_sign(result);
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/* Check for zero */
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if (srcp1 == 0 && srcp2 == 0) {
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Sgl_setzero(result);
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*dstptr = result;
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return(NOEXCEPTION);
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}
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}
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/*
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* Generate exponent and normalized mantissa
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*/
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dst_exponent = 16; /* initialize for normalization */
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if (srcp1 == 0) {
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/*
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* Check word for most significant bit set. Returns
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* a value in dst_exponent indicating the bit position,
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* between -1 and 30.
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*/
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Find_ms_one_bit(srcp2,dst_exponent);
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/* left justify source, with msb at bit position 1 */
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if (dst_exponent >= 0) {
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srcp1 = srcp2 << dst_exponent;
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srcp2 = 0;
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}
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else {
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srcp1 = srcp2 >> 1;
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srcp2 <<= 31;
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}
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/*
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* since msb set is in second word, need to
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* adjust bit position count
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*/
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dst_exponent += 32;
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}
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else {
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/*
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* Check word for most significant bit set. Returns
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* a value in dst_exponent indicating the bit position,
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* between -1 and 30.
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*
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*/
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Find_ms_one_bit(srcp1,dst_exponent);
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/* left justify source, with msb at bit position 1 */
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if (dst_exponent > 0) {
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Variable_shift_double(srcp1,srcp2,(32-dst_exponent),
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srcp1);
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srcp2 <<= dst_exponent;
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}
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/*
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* If dst_exponent = 0, we don't need to shift anything.
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* If dst_exponent = -1, src = - 2**63 so we won't need to
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* shift srcp2.
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*/
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else srcp1 >>= -(dst_exponent);
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}
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Sgl_set_mantissa(result, srcp1 >> SGL_EXP_LENGTH - 1);
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Sgl_set_exponent(result, (62+SGL_BIAS) - dst_exponent);
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/* check for inexact */
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if (Dint_isinexact_to_sgl(srcp1,srcp2)) {
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switch (Rounding_mode()) {
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case ROUNDPLUS:
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if (Sgl_iszero_sign(result))
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Sgl_increment(result);
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break;
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case ROUNDMINUS:
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if (Sgl_isone_sign(result))
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Sgl_increment(result);
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break;
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case ROUNDNEAREST:
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Sgl_roundnearest_from_dint(srcp1,srcp2,result);
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}
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if (Is_inexacttrap_enabled()) {
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*dstptr = result;
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return(INEXACTEXCEPTION);
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}
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else Set_inexactflag();
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}
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*dstptr = result;
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return(NOEXCEPTION);
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}
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/*
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* Double Fixed-point to Double Floating-point
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*/
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int
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dbl_to_dbl_fcnvxf(
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dbl_integer *srcptr,
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unsigned int *nullptr,
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dbl_floating_point *dstptr,
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unsigned int *status)
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{
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register int srcp1, dst_exponent;
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register unsigned int srcp2, resultp1 = 0, resultp2 = 0;
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Dint_copyfromptr(srcptr,srcp1,srcp2);
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/*
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* set sign bit of result and get magnitude of source
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*/
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if (srcp1 < 0) {
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Dbl_setone_sign(resultp1);
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Dint_negate(srcp1,srcp2);
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}
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else {
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Dbl_setzero_sign(resultp1);
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/* Check for zero */
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if (srcp1 == 0 && srcp2 ==0) {
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Dbl_setzero(resultp1,resultp2);
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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}
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/*
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* Generate exponent and normalized mantissa
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*/
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dst_exponent = 16; /* initialize for normalization */
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if (srcp1 == 0) {
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/*
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* Check word for most significant bit set. Returns
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* a value in dst_exponent indicating the bit position,
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* between -1 and 30.
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*/
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Find_ms_one_bit(srcp2,dst_exponent);
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/* left justify source, with msb at bit position 1 */
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if (dst_exponent >= 0) {
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srcp1 = srcp2 << dst_exponent;
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srcp2 = 0;
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}
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else {
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srcp1 = srcp2 >> 1;
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srcp2 <<= 31;
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}
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/*
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* since msb set is in second word, need to
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* adjust bit position count
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*/
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dst_exponent += 32;
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}
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else {
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/*
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* Check word for most significant bit set. Returns
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* a value in dst_exponent indicating the bit position,
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* between -1 and 30.
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*/
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Find_ms_one_bit(srcp1,dst_exponent);
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/* left justify source, with msb at bit position 1 */
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if (dst_exponent > 0) {
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Variable_shift_double(srcp1,srcp2,(32-dst_exponent),
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srcp1);
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srcp2 <<= dst_exponent;
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}
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/*
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* If dst_exponent = 0, we don't need to shift anything.
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* If dst_exponent = -1, src = - 2**63 so we won't need to
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* shift srcp2.
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*/
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else srcp1 >>= -(dst_exponent);
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}
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Dbl_set_mantissap1(resultp1, srcp1 >> (DBL_EXP_LENGTH-1));
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Shiftdouble(srcp1,srcp2,DBL_EXP_LENGTH-1,resultp2);
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Dbl_set_exponent(resultp1, (62+DBL_BIAS) - dst_exponent);
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/* check for inexact */
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if (Dint_isinexact_to_dbl(srcp2)) {
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switch (Rounding_mode()) {
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case ROUNDPLUS:
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if (Dbl_iszero_sign(resultp1)) {
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Dbl_increment(resultp1,resultp2);
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}
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break;
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case ROUNDMINUS:
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if (Dbl_isone_sign(resultp1)) {
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Dbl_increment(resultp1,resultp2);
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}
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break;
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case ROUNDNEAREST:
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Dbl_roundnearest_from_dint(srcp2,resultp1,
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resultp2);
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}
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if (Is_inexacttrap_enabled()) {
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(INEXACTEXCEPTION);
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}
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else Set_inexactflag();
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}
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Dbl_copytoptr(resultp1,resultp2,dstptr);
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return(NOEXCEPTION);
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}
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