fcnvff.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 *  File:
 12 *	@(#)	pa/spmath/fcnvff.c		$Revision: 1.1 $
 13 *
 14 *  Purpose:
 15 *	Single Floating-point to Double Floating-point
 16 *	Double Floating-point to Single Floating-point
 17 *
 18 *  External Interfaces:
 19 *	dbl_to_sgl_fcnvff(srcptr,_nullptr,dstptr,status)
 20 *	sgl_to_dbl_fcnvff(srcptr,_nullptr,dstptr,status)
 21 *
 22 *  Internal Interfaces:
 23 *
 24 *  Theory:
 25 *	<<please update with a overview of the operation of this file>>
 26 *
 27 * END_DESC
 28*/
 29
 30
 31#include "float.h"
 32#include "sgl_float.h"
 33#include "dbl_float.h"
 34#include "cnv_float.h"
 35
 36/*
 37 *  Single Floating-point to Double Floating-point 
 38 */
 39/*ARGSUSED*/
 40int
 41sgl_to_dbl_fcnvff(
 42	    sgl_floating_point *srcptr,
 43	    unsigned int *_nullptr,
 44	    dbl_floating_point *dstptr,
 45	    unsigned int *status)
 46{
 47	register unsigned int src, resultp1, resultp2;
 48	register int src_exponent;
 49
 50	src = *srcptr;
 51	src_exponent = Sgl_exponent(src);
 52	Dbl_allp1(resultp1) = Sgl_all(src);  /* set sign of result */
 53	/* 
 54 	 * Test for NaN or infinity
 55 	 */
 56	if (src_exponent == SGL_INFINITY_EXPONENT) {
 57		/*
 58		 * determine if NaN or infinity
 59		 */
 60		if (Sgl_iszero_mantissa(src)) {
 61			/*
 62			 * is infinity; want to return double infinity
 63			 */
 64			Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
 65			Dbl_copytoptr(resultp1,resultp2,dstptr);
 66			return(NOEXCEPTION);
 67		}
 68		else {
 69			/* 
 70			 * is NaN; signaling or quiet?
 71			 */
 72			if (Sgl_isone_signaling(src)) {
 73				/* trap if INVALIDTRAP enabled */
 74				if (Is_invalidtrap_enabled())
 75					return(INVALIDEXCEPTION);
 76				/* make NaN quiet */
 77				else {
 78					Set_invalidflag();
 79					Sgl_set_quiet(src);
 80				}
 81			}
 82			/* 
 83			 * NaN is quiet, return as double NaN 
 84			 */
 85			Dbl_setinfinity_exponent(resultp1);
 86			Sgl_to_dbl_mantissa(src,resultp1,resultp2);
 87			Dbl_copytoptr(resultp1,resultp2,dstptr);
 88			return(NOEXCEPTION);
 89		}
 90	}
 91	/* 
 92 	 * Test for zero or denormalized
 93 	 */
 94	if (src_exponent == 0) {
 95		/*
 96		 * determine if zero or denormalized
 97		 */
 98		if (Sgl_isnotzero_mantissa(src)) {
 99			/*
100			 * is denormalized; want to normalize
101			 */
102			Sgl_clear_signexponent(src);
103			Sgl_leftshiftby1(src);
104			Sgl_normalize(src,src_exponent);
105			Sgl_to_dbl_exponent(src_exponent,resultp1);
106			Sgl_to_dbl_mantissa(src,resultp1,resultp2);
107		}
108		else {
109			Dbl_setzero_exponentmantissa(resultp1,resultp2);
110		}
111		Dbl_copytoptr(resultp1,resultp2,dstptr);
112		return(NOEXCEPTION);
113	}
114	/*
115	 * No special cases, just complete the conversion
116	 */
117	Sgl_to_dbl_exponent(src_exponent, resultp1);
118	Sgl_to_dbl_mantissa(Sgl_mantissa(src), resultp1,resultp2);
119	Dbl_copytoptr(resultp1,resultp2,dstptr);
120	return(NOEXCEPTION);
121}
122
123/*
124 *  Double Floating-point to Single Floating-point 
125 */
126/*ARGSUSED*/
127int
128dbl_to_sgl_fcnvff(
129		    dbl_floating_point *srcptr,
130		    unsigned int *_nullptr,
131		    sgl_floating_point *dstptr,
132		    unsigned int *status)
133{
134        register unsigned int srcp1, srcp2, result;
135        register int src_exponent, dest_exponent, dest_mantissa;
136        register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE;
137	register boolean lsb_odd = FALSE;
138	boolean is_tiny = FALSE;
139
140	Dbl_copyfromptr(srcptr,srcp1,srcp2);
141        src_exponent = Dbl_exponent(srcp1);
142	Sgl_all(result) = Dbl_allp1(srcp1);  /* set sign of result */
143        /* 
144         * Test for NaN or infinity
145         */
146        if (src_exponent == DBL_INFINITY_EXPONENT) {
147                /*
148                 * determine if NaN or infinity
149                 */
150                if (Dbl_iszero_mantissa(srcp1,srcp2)) {
151                        /*
152                         * is infinity; want to return single infinity
153                         */
154                        Sgl_setinfinity_exponentmantissa(result);
155                        *dstptr = result;
156                        return(NOEXCEPTION);
157                }
158                /* 
159                 * is NaN; signaling or quiet?
160                 */
161                if (Dbl_isone_signaling(srcp1)) {
162                        /* trap if INVALIDTRAP enabled */
163                        if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
164                        else {
165				Set_invalidflag();
166                        	/* make NaN quiet */
167                        	Dbl_set_quiet(srcp1);
168			}
169                }
170                /* 
171                 * NaN is quiet, return as single NaN 
172                 */
173                Sgl_setinfinity_exponent(result);
174		Sgl_set_mantissa(result,Dallp1(srcp1)<<3 | Dallp2(srcp2)>>29);
175		if (Sgl_iszero_mantissa(result)) Sgl_set_quiet(result);
176                *dstptr = result;
177                return(NOEXCEPTION);
178        }
179        /*
180         * Generate result
181         */
182        Dbl_to_sgl_exponent(src_exponent,dest_exponent);
183	if (dest_exponent > 0) {
184        	Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact,guardbit, 
185		stickybit,lsb_odd);
186	}
187	else {
188		if (Dbl_iszero_exponentmantissa(srcp1,srcp2)){
189			Sgl_setzero_exponentmantissa(result);
190			*dstptr = result;
191			return(NOEXCEPTION);
192		}
193                if (Is_underflowtrap_enabled()) {
194			Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact,
195			guardbit,stickybit,lsb_odd);
196                }
197		else {
198			/* compute result, determine inexact info,
199			 * and set Underflowflag if appropriate
200			 */
201			Dbl_to_sgl_denormalized(srcp1,srcp2,dest_exponent,
202			dest_mantissa,inexact,guardbit,stickybit,lsb_odd,
203			is_tiny);
204		}
205	}
206        /* 
207         * Now round result if not exact
208         */
209        if (inexact) {
210                switch (Rounding_mode()) {
211                        case ROUNDPLUS: 
212                                if (Sgl_iszero_sign(result)) dest_mantissa++;
213                                break;
214                        case ROUNDMINUS: 
215                                if (Sgl_isone_sign(result)) dest_mantissa++;
216                                break;
217                        case ROUNDNEAREST:
218                                if (guardbit) {
219                                   if (stickybit || lsb_odd) dest_mantissa++;
220                                   }
221                }
222        }
223        Sgl_set_exponentmantissa(result,dest_mantissa);
224
225        /*
226         * check for mantissa overflow after rounding
227         */
228        if ((dest_exponent>0 || Is_underflowtrap_enabled()) && 
229	    Sgl_isone_hidden(result)) dest_exponent++;
230
231        /* 
232         * Test for overflow
233         */
234        if (dest_exponent >= SGL_INFINITY_EXPONENT) {
235                /* trap if OVERFLOWTRAP enabled */
236                if (Is_overflowtrap_enabled()) {
237                        /* 
238                         * Check for gross overflow
239                         */
240                        if (dest_exponent >= SGL_INFINITY_EXPONENT+SGL_WRAP) 
241                        	return(UNIMPLEMENTEDEXCEPTION);
242                        
243                        /*
244                         * Adjust bias of result
245                         */
246			Sgl_setwrapped_exponent(result,dest_exponent,ovfl);
247			*dstptr = result;
248			if (inexact) 
249			    if (Is_inexacttrap_enabled())
250				return(OVERFLOWEXCEPTION|INEXACTEXCEPTION);
251			    else Set_inexactflag();
252                        return(OVERFLOWEXCEPTION);
253                }
254                Set_overflowflag();
255		inexact = TRUE;
256		/* set result to infinity or largest number */
257		Sgl_setoverflow(result);
258        }
259        /* 
260         * Test for underflow
261         */
262        else if (dest_exponent <= 0) {
263                /* trap if UNDERFLOWTRAP enabled */
264                if (Is_underflowtrap_enabled()) {
265                        /* 
266                         * Check for gross underflow
267                         */
268                        if (dest_exponent <= -(SGL_WRAP))
269                        	return(UNIMPLEMENTEDEXCEPTION);
270                        /*
271                         * Adjust bias of result
272                         */
273			Sgl_setwrapped_exponent(result,dest_exponent,unfl);
274			*dstptr = result;
275			if (inexact) 
276			    if (Is_inexacttrap_enabled())
277				return(UNDERFLOWEXCEPTION|INEXACTEXCEPTION);
278			    else Set_inexactflag();
279                        return(UNDERFLOWEXCEPTION);
280                }
281                 /* 
282                  * result is denormalized or signed zero
283                  */
284               if (inexact && is_tiny) Set_underflowflag();
285
286        }
287	else Sgl_set_exponent(result,dest_exponent);
288	*dstptr = result;
289        /* 
290         * Trap if inexact trap is enabled
291         */
292        if (inexact)
293        	if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
294        	else Set_inexactflag();
295        return(NOEXCEPTION);
296}