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/sfdiv.c $Revision: 1.1 $ |
13 | * |
14 | * Purpose: |
15 | * Single Precision Floating-point Divide |
16 | * |
17 | * External Interfaces: |
18 | * sgl_fdiv(srcptr1,srcptr2,dstptr,status) |
19 | * |
20 | * Internal Interfaces: |
21 | * |
22 | * Theory: |
23 | * <<please update with a overview of the operation of this file>> |
24 | * |
25 | * END_DESC |
26 | */ |
27 | |
28 | |
29 | #include "float.h" |
30 | #include "sgl_float.h" |
31 | |
32 | /* |
33 | * Single Precision Floating-point Divide |
34 | */ |
35 | |
36 | int |
37 | sgl_fdiv (sgl_floating_point * srcptr1, sgl_floating_point * srcptr2, |
38 | sgl_floating_point * dstptr, unsigned int *status) |
39 | { |
40 | register unsigned int opnd1, opnd2, opnd3, result; |
41 | register int dest_exponent, count; |
42 | register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE; |
43 | boolean is_tiny; |
44 | |
45 | opnd1 = *srcptr1; |
46 | opnd2 = *srcptr2; |
47 | /* |
48 | * set sign bit of result |
49 | */ |
50 | if (Sgl_sign(opnd1) ^ Sgl_sign(opnd2)) Sgl_setnegativezero(result); |
51 | else Sgl_setzero(result); |
52 | /* |
53 | * check first operand for NaN's or infinity |
54 | */ |
55 | if (Sgl_isinfinity_exponent(opnd1)) { |
56 | if (Sgl_iszero_mantissa(opnd1)) { |
57 | if (Sgl_isnotnan(opnd2)) { |
58 | if (Sgl_isinfinity(opnd2)) { |
59 | /* |
60 | * invalid since both operands |
61 | * are infinity |
62 | */ |
63 | if (Is_invalidtrap_enabled()) |
64 | return(INVALIDEXCEPTION); |
65 | Set_invalidflag(); |
66 | Sgl_makequietnan(result); |
67 | *dstptr = result; |
68 | return(NOEXCEPTION); |
69 | } |
70 | /* |
71 | * return infinity |
72 | */ |
73 | Sgl_setinfinity_exponentmantissa(result); |
74 | *dstptr = result; |
75 | return(NOEXCEPTION); |
76 | } |
77 | } |
78 | else { |
79 | /* |
80 | * is NaN; signaling or quiet? |
81 | */ |
82 | if (Sgl_isone_signaling(opnd1)) { |
83 | /* trap if INVALIDTRAP enabled */ |
84 | if (Is_invalidtrap_enabled()) |
85 | return(INVALIDEXCEPTION); |
86 | /* make NaN quiet */ |
87 | Set_invalidflag(); |
88 | Sgl_set_quiet(opnd1); |
89 | } |
90 | /* |
91 | * is second operand a signaling NaN? |
92 | */ |
93 | else if (Sgl_is_signalingnan(opnd2)) { |
94 | /* trap if INVALIDTRAP enabled */ |
95 | if (Is_invalidtrap_enabled()) |
96 | return(INVALIDEXCEPTION); |
97 | /* make NaN quiet */ |
98 | Set_invalidflag(); |
99 | Sgl_set_quiet(opnd2); |
100 | *dstptr = opnd2; |
101 | return(NOEXCEPTION); |
102 | } |
103 | /* |
104 | * return quiet NaN |
105 | */ |
106 | *dstptr = opnd1; |
107 | return(NOEXCEPTION); |
108 | } |
109 | } |
110 | /* |
111 | * check second operand for NaN's or infinity |
112 | */ |
113 | if (Sgl_isinfinity_exponent(opnd2)) { |
114 | if (Sgl_iszero_mantissa(opnd2)) { |
115 | /* |
116 | * return zero |
117 | */ |
118 | Sgl_setzero_exponentmantissa(result); |
119 | *dstptr = result; |
120 | return(NOEXCEPTION); |
121 | } |
122 | /* |
123 | * is NaN; signaling or quiet? |
124 | */ |
125 | if (Sgl_isone_signaling(opnd2)) { |
126 | /* trap if INVALIDTRAP enabled */ |
127 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
128 | /* make NaN quiet */ |
129 | Set_invalidflag(); |
130 | Sgl_set_quiet(opnd2); |
131 | } |
132 | /* |
133 | * return quiet NaN |
134 | */ |
135 | *dstptr = opnd2; |
136 | return(NOEXCEPTION); |
137 | } |
138 | /* |
139 | * check for division by zero |
140 | */ |
141 | if (Sgl_iszero_exponentmantissa(opnd2)) { |
142 | if (Sgl_iszero_exponentmantissa(opnd1)) { |
143 | /* invalid since both operands are zero */ |
144 | if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION); |
145 | Set_invalidflag(); |
146 | Sgl_makequietnan(result); |
147 | *dstptr = result; |
148 | return(NOEXCEPTION); |
149 | } |
150 | if (Is_divisionbyzerotrap_enabled()) |
151 | return(DIVISIONBYZEROEXCEPTION); |
152 | Set_divisionbyzeroflag(); |
153 | Sgl_setinfinity_exponentmantissa(result); |
154 | *dstptr = result; |
155 | return(NOEXCEPTION); |
156 | } |
157 | /* |
158 | * Generate exponent |
159 | */ |
160 | dest_exponent = Sgl_exponent(opnd1) - Sgl_exponent(opnd2) + SGL_BIAS; |
161 | |
162 | /* |
163 | * Generate mantissa |
164 | */ |
165 | if (Sgl_isnotzero_exponent(opnd1)) { |
166 | /* set hidden bit */ |
167 | Sgl_clear_signexponent_set_hidden(opnd1); |
168 | } |
169 | else { |
170 | /* check for zero */ |
171 | if (Sgl_iszero_mantissa(opnd1)) { |
172 | Sgl_setzero_exponentmantissa(result); |
173 | *dstptr = result; |
174 | return(NOEXCEPTION); |
175 | } |
176 | /* is denormalized; want to normalize */ |
177 | Sgl_clear_signexponent(opnd1); |
178 | Sgl_leftshiftby1(opnd1); |
179 | Sgl_normalize(opnd1,dest_exponent); |
180 | } |
181 | /* opnd2 needs to have hidden bit set with msb in hidden bit */ |
182 | if (Sgl_isnotzero_exponent(opnd2)) { |
183 | Sgl_clear_signexponent_set_hidden(opnd2); |
184 | } |
185 | else { |
186 | /* is denormalized; want to normalize */ |
187 | Sgl_clear_signexponent(opnd2); |
188 | Sgl_leftshiftby1(opnd2); |
189 | while(Sgl_iszero_hiddenhigh7mantissa(opnd2)) { |
190 | Sgl_leftshiftby8(opnd2); |
191 | dest_exponent += 8; |
192 | } |
193 | if(Sgl_iszero_hiddenhigh3mantissa(opnd2)) { |
194 | Sgl_leftshiftby4(opnd2); |
195 | dest_exponent += 4; |
196 | } |
197 | while(Sgl_iszero_hidden(opnd2)) { |
198 | Sgl_leftshiftby1(opnd2); |
199 | dest_exponent += 1; |
200 | } |
201 | } |
202 | |
203 | /* Divide the source mantissas */ |
204 | |
205 | /* |
206 | * A non_restoring divide algorithm is used. |
207 | */ |
208 | Sgl_subtract(opnd1,opnd2,opnd1); |
209 | Sgl_setzero(opnd3); |
210 | for (count=1;count<=SGL_P && Sgl_all(opnd1);count++) { |
211 | Sgl_leftshiftby1(opnd1); |
212 | Sgl_leftshiftby1(opnd3); |
213 | if (Sgl_iszero_sign(opnd1)) { |
214 | Sgl_setone_lowmantissa(opnd3); |
215 | Sgl_subtract(opnd1,opnd2,opnd1); |
216 | } |
217 | else Sgl_addition(opnd1,opnd2,opnd1); |
218 | } |
219 | if (count <= SGL_P) { |
220 | Sgl_leftshiftby1(opnd3); |
221 | Sgl_setone_lowmantissa(opnd3); |
222 | Sgl_leftshift(opnd3,SGL_P-count); |
223 | if (Sgl_iszero_hidden(opnd3)) { |
224 | Sgl_leftshiftby1(opnd3); |
225 | dest_exponent--; |
226 | } |
227 | } |
228 | else { |
229 | if (Sgl_iszero_hidden(opnd3)) { |
230 | /* need to get one more bit of result */ |
231 | Sgl_leftshiftby1(opnd1); |
232 | Sgl_leftshiftby1(opnd3); |
233 | if (Sgl_iszero_sign(opnd1)) { |
234 | Sgl_setone_lowmantissa(opnd3); |
235 | Sgl_subtract(opnd1,opnd2,opnd1); |
236 | } |
237 | else Sgl_addition(opnd1,opnd2,opnd1); |
238 | dest_exponent--; |
239 | } |
240 | if (Sgl_iszero_sign(opnd1)) guardbit = TRUE; |
241 | stickybit = Sgl_all(opnd1); |
242 | } |
243 | inexact = guardbit | stickybit; |
244 | |
245 | /* |
246 | * round result |
247 | */ |
248 | if (inexact && (dest_exponent > 0 || Is_underflowtrap_enabled())) { |
249 | Sgl_clear_signexponent(opnd3); |
250 | switch (Rounding_mode()) { |
251 | case ROUNDPLUS: |
252 | if (Sgl_iszero_sign(result)) |
253 | Sgl_increment_mantissa(opnd3); |
254 | break; |
255 | case ROUNDMINUS: |
256 | if (Sgl_isone_sign(result)) |
257 | Sgl_increment_mantissa(opnd3); |
258 | break; |
259 | case ROUNDNEAREST: |
260 | if (guardbit) { |
261 | if (stickybit || Sgl_isone_lowmantissa(opnd3)) |
262 | Sgl_increment_mantissa(opnd3); |
263 | } |
264 | } |
265 | if (Sgl_isone_hidden(opnd3)) dest_exponent++; |
266 | } |
267 | Sgl_set_mantissa(result,opnd3); |
268 | |
269 | /* |
270 | * Test for overflow |
271 | */ |
272 | if (dest_exponent >= SGL_INFINITY_EXPONENT) { |
273 | /* trap if OVERFLOWTRAP enabled */ |
274 | if (Is_overflowtrap_enabled()) { |
275 | /* |
276 | * Adjust bias of result |
277 | */ |
278 | Sgl_setwrapped_exponent(result,dest_exponent,ovfl); |
279 | *dstptr = result; |
280 | if (inexact) |
281 | if (Is_inexacttrap_enabled()) |
282 | return(OVERFLOWEXCEPTION | INEXACTEXCEPTION); |
283 | else Set_inexactflag(); |
284 | return(OVERFLOWEXCEPTION); |
285 | } |
286 | Set_overflowflag(); |
287 | /* set result to infinity or largest number */ |
288 | Sgl_setoverflow(result); |
289 | inexact = TRUE; |
290 | } |
291 | /* |
292 | * Test for underflow |
293 | */ |
294 | else if (dest_exponent <= 0) { |
295 | /* trap if UNDERFLOWTRAP enabled */ |
296 | if (Is_underflowtrap_enabled()) { |
297 | /* |
298 | * Adjust bias of result |
299 | */ |
300 | Sgl_setwrapped_exponent(result,dest_exponent,unfl); |
301 | *dstptr = result; |
302 | if (inexact) |
303 | if (Is_inexacttrap_enabled()) |
304 | return(UNDERFLOWEXCEPTION | INEXACTEXCEPTION); |
305 | else Set_inexactflag(); |
306 | return(UNDERFLOWEXCEPTION); |
307 | } |
308 | |
309 | /* Determine if should set underflow flag */ |
310 | is_tiny = TRUE; |
311 | if (dest_exponent == 0 && inexact) { |
312 | switch (Rounding_mode()) { |
313 | case ROUNDPLUS: |
314 | if (Sgl_iszero_sign(result)) { |
315 | Sgl_increment(opnd3); |
316 | if (Sgl_isone_hiddenoverflow(opnd3)) |
317 | is_tiny = FALSE; |
318 | Sgl_decrement(opnd3); |
319 | } |
320 | break; |
321 | case ROUNDMINUS: |
322 | if (Sgl_isone_sign(result)) { |
323 | Sgl_increment(opnd3); |
324 | if (Sgl_isone_hiddenoverflow(opnd3)) |
325 | is_tiny = FALSE; |
326 | Sgl_decrement(opnd3); |
327 | } |
328 | break; |
329 | case ROUNDNEAREST: |
330 | if (guardbit && (stickybit || |
331 | Sgl_isone_lowmantissa(opnd3))) { |
332 | Sgl_increment(opnd3); |
333 | if (Sgl_isone_hiddenoverflow(opnd3)) |
334 | is_tiny = FALSE; |
335 | Sgl_decrement(opnd3); |
336 | } |
337 | break; |
338 | } |
339 | } |
340 | |
341 | /* |
342 | * denormalize result or set to signed zero |
343 | */ |
344 | stickybit = inexact; |
345 | Sgl_denormalize(opnd3,dest_exponent,guardbit,stickybit,inexact); |
346 | |
347 | /* return rounded number */ |
348 | if (inexact) { |
349 | switch (Rounding_mode()) { |
350 | case ROUNDPLUS: |
351 | if (Sgl_iszero_sign(result)) { |
352 | Sgl_increment(opnd3); |
353 | } |
354 | break; |
355 | case ROUNDMINUS: |
356 | if (Sgl_isone_sign(result)) { |
357 | Sgl_increment(opnd3); |
358 | } |
359 | break; |
360 | case ROUNDNEAREST: |
361 | if (guardbit && (stickybit || |
362 | Sgl_isone_lowmantissa(opnd3))) { |
363 | Sgl_increment(opnd3); |
364 | } |
365 | break; |
366 | } |
367 | if (is_tiny) Set_underflowflag(); |
368 | } |
369 | Sgl_set_exponentmantissa(result,opnd3); |
370 | } |
371 | else Sgl_set_exponent(result,dest_exponent); |
372 | *dstptr = result; |
373 | /* check for inexact */ |
374 | if (inexact) { |
375 | if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION); |
376 | else Set_inexactflag(); |
377 | } |
378 | return(NOEXCEPTION); |
379 | } |
380 | |