frnd.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
  4 *
  5 * Floating-point emulation code
  6 *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
  7 */
  8/*
  9 * BEGIN_DESC
 10 *
 11 *  Purpose:
 12 *	Single Floating-point Round to Integer
 13 *	Double Floating-point Round to Integer
 14 *	Quad Floating-point Round to Integer (returns unimplemented)
 15 *
 16 *  External Interfaces:
 17 *	dbl_frnd(srcptr,_nullptr,dstptr,status)
 18 *	sgl_frnd(srcptr,_nullptr,dstptr,status)
 19 *
 20 * END_DESC
 21*/
 22
 23
 24#include "float.h"
 25#include "sgl_float.h"
 26#include "dbl_float.h"
 27#include "cnv_float.h"
 28
 29/*
 30 *  Single Floating-point Round to Integer
 31 */
 32
 33/*ARGSUSED*/
 34int
 35sgl_frnd(sgl_floating_point *srcptr,
 36	unsigned int *_nullptr,
 37	sgl_floating_point *dstptr,
 38	unsigned int *status)
 39{
 40	register unsigned int src, result;
 41	register int src_exponent;
 42	register boolean inexact = FALSE;
 43
 44	src = *srcptr;
 45        /*
 46         * check source operand for NaN or infinity
 47         */
 48        if ((src_exponent = Sgl_exponent(src)) == SGL_INFINITY_EXPONENT) {
 49                /*
 50                 * is signaling NaN?
 51                 */
 52                if (Sgl_isone_signaling(src)) {
 53                        /* trap if INVALIDTRAP enabled */
 54                        if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
 55                        /* make NaN quiet */
 56                        Set_invalidflag();
 57                        Sgl_set_quiet(src);
 58                }
 59                /*
 60                 * return quiet NaN or infinity
 61                 */
 62                *dstptr = src;
 63                return(NOEXCEPTION);
 64        }
 65	/* 
 66	 * Need to round?
 67	 */
 68	if ((src_exponent -= SGL_BIAS) >= SGL_P - 1) {
 69		*dstptr = src;
 70		return(NOEXCEPTION);
 71	}
 72	/*
 73	 * Generate result
 74	 */
 75	if (src_exponent >= 0) {
 76		Sgl_clear_exponent_set_hidden(src);
 77		result = src;
 78		Sgl_rightshift(result,(SGL_P-1) - (src_exponent));
 79		/* check for inexact */
 80		if (Sgl_isinexact_to_fix(src,src_exponent)) {
 81			inexact = TRUE;
 82			/*  round result  */
 83			switch (Rounding_mode()) {
 84			case ROUNDPLUS:
 85			     if (Sgl_iszero_sign(src)) Sgl_increment(result);
 86			     break;
 87			case ROUNDMINUS:
 88			     if (Sgl_isone_sign(src)) Sgl_increment(result);
 89			     break;
 90			case ROUNDNEAREST:
 91			     if (Sgl_isone_roundbit(src,src_exponent))
 92			        if (Sgl_isone_stickybit(src,src_exponent) 
 93				|| (Sgl_isone_lowmantissa(result))) 
 94					Sgl_increment(result);
 95			} 
 96		}
 97		Sgl_leftshift(result,(SGL_P-1) - (src_exponent));
 98		if (Sgl_isone_hiddenoverflow(result)) 
 99			Sgl_set_exponent(result,src_exponent + (SGL_BIAS+1));
100		else Sgl_set_exponent(result,src_exponent + SGL_BIAS);
101	}
102	else {
103		result = src;  		/* set sign */
104		Sgl_setzero_exponentmantissa(result);
105		/* check for inexact */
106		if (Sgl_isnotzero_exponentmantissa(src)) {
107			inexact = TRUE;
108			/*  round result  */
109			switch (Rounding_mode()) {
110			case ROUNDPLUS:
111			     if (Sgl_iszero_sign(src)) 
112				Sgl_set_exponent(result,SGL_BIAS);
113			     break;
114			case ROUNDMINUS:
115			     if (Sgl_isone_sign(src)) 
116				Sgl_set_exponent(result,SGL_BIAS);
117			     break;
118			case ROUNDNEAREST:
119			     if (src_exponent == -1)
120			        if (Sgl_isnotzero_mantissa(src))
121				   Sgl_set_exponent(result,SGL_BIAS);
122			} 
123		}
124	}
125	*dstptr = result;
126	if (inexact) {
127		if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
128		else Set_inexactflag();
129	}
130	return(NOEXCEPTION);
131} 
132
133/*
134 *  Double Floating-point Round to Integer
135 */
136
137/*ARGSUSED*/
138int
139dbl_frnd(
140	dbl_floating_point *srcptr,
141	unsigned int *_nullptr,
142	dbl_floating_point *dstptr,
143	unsigned int *status)
144{
145	register unsigned int srcp1, srcp2, resultp1, resultp2;
146	register int src_exponent;
147	register boolean inexact = FALSE;
148
149	Dbl_copyfromptr(srcptr,srcp1,srcp2);
150        /*
151         * check source operand for NaN or infinity
152         */
153        if ((src_exponent = Dbl_exponent(srcp1)) == DBL_INFINITY_EXPONENT) {
154                /*
155                 * is signaling NaN?
156                 */
157                if (Dbl_isone_signaling(srcp1)) {
158                        /* trap if INVALIDTRAP enabled */
159                        if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
160                        /* make NaN quiet */
161                        Set_invalidflag();
162                        Dbl_set_quiet(srcp1);
163                }
164                /*
165                 * return quiet NaN or infinity
166                 */
167                Dbl_copytoptr(srcp1,srcp2,dstptr);
168                return(NOEXCEPTION);
169        }
170	/* 
171	 * Need to round?
172	 */
173	if ((src_exponent -= DBL_BIAS) >= DBL_P - 1) {
174		Dbl_copytoptr(srcp1,srcp2,dstptr);
175		return(NOEXCEPTION);
176	}
177	/*
178	 * Generate result
179	 */
180	if (src_exponent >= 0) {
181		Dbl_clear_exponent_set_hidden(srcp1);
182		resultp1 = srcp1;
183		resultp2 = srcp2;
184		Dbl_rightshift(resultp1,resultp2,(DBL_P-1) - (src_exponent));
185		/* check for inexact */
186		if (Dbl_isinexact_to_fix(srcp1,srcp2,src_exponent)) {
187			inexact = TRUE;
188			/*  round result  */
189			switch (Rounding_mode()) {
190			case ROUNDPLUS:
191			     if (Dbl_iszero_sign(srcp1)) 
192				Dbl_increment(resultp1,resultp2);
193			     break;
194			case ROUNDMINUS:
195			     if (Dbl_isone_sign(srcp1)) 
196				Dbl_increment(resultp1,resultp2);
197			     break;
198			case ROUNDNEAREST:
199			     if (Dbl_isone_roundbit(srcp1,srcp2,src_exponent))
200			      if (Dbl_isone_stickybit(srcp1,srcp2,src_exponent) 
201				  || (Dbl_isone_lowmantissap2(resultp2))) 
202					Dbl_increment(resultp1,resultp2);
203			} 
204		}
205		Dbl_leftshift(resultp1,resultp2,(DBL_P-1) - (src_exponent));
206		if (Dbl_isone_hiddenoverflow(resultp1))
207			Dbl_set_exponent(resultp1,src_exponent + (DBL_BIAS+1));
208		else Dbl_set_exponent(resultp1,src_exponent + DBL_BIAS);
209	}
210	else {
211		resultp1 = srcp1;  /* set sign */
212		Dbl_setzero_exponentmantissa(resultp1,resultp2);
213		/* check for inexact */
214		if (Dbl_isnotzero_exponentmantissa(srcp1,srcp2)) {
215			inexact = TRUE;
216			/*  round result  */
217			switch (Rounding_mode()) {
218			case ROUNDPLUS:
219			     if (Dbl_iszero_sign(srcp1)) 
220				Dbl_set_exponent(resultp1,DBL_BIAS);
221			     break;
222			case ROUNDMINUS:
223			     if (Dbl_isone_sign(srcp1)) 
224				Dbl_set_exponent(resultp1,DBL_BIAS);
225			     break;
226			case ROUNDNEAREST:
227			     if (src_exponent == -1)
228			        if (Dbl_isnotzero_mantissa(srcp1,srcp2))
229				   Dbl_set_exponent(resultp1,DBL_BIAS);
230			} 
231		}
232	}
233	Dbl_copytoptr(resultp1,resultp2,dstptr);
234	if (inexact) {
235		if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
236		else Set_inexactflag();
237	}
238	return(NOEXCEPTION);
239}