blob: acf409144763775b3d3a43377ffb9fa11bfb2feb [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001
2/*
3===============================================================================
4
5This C source fragment is part of the SoftFloat IEC/IEEE Floating-point
6Arithmetic Package, Release 2.
7
8Written by John R. Hauser. This work was made possible in part by the
9International Computer Science Institute, located at Suite 600, 1947 Center
10Street, Berkeley, California 94704. Funding was partially provided by the
11National Science Foundation under grant MIP-9311980. The original version
12of this code was written as part of a project to build a fixed-point vector
13processor in collaboration with the University of California at Berkeley,
14overseen by Profs. Nelson Morgan and John Wawrzynek. More information
15is available through the Web page `http://HTTP.CS.Berkeley.EDU/~jhauser/
16arithmetic/softfloat.html'.
17
18THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE. Although reasonable effort
19has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT
20TIMES RESULT IN INCORRECT BEHAVIOR. USE OF THIS SOFTWARE IS RESTRICTED TO
21PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY
22AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE.
23
24Derivative works are acceptable, even for commercial purposes, so long as
25(1) they include prominent notice that the work is derivative, and (2) they
26include prominent notice akin to these three paragraphs for those parts of
27this code that are retained.
28
29===============================================================================
30*/
31
32/*
33-------------------------------------------------------------------------------
34Underflow tininess-detection mode, statically initialized to default value.
35(The declaration in `softfloat.h' must match the `int8' type here.)
36-------------------------------------------------------------------------------
37*/
38int8 float_detect_tininess = float_tininess_after_rounding;
39
40/*
41-------------------------------------------------------------------------------
42Raises the exceptions specified by `flags'. Floating-point traps can be
43defined here if desired. It is currently not possible for such a trap to
44substitute a result value. If traps are not implemented, this routine
45should be simply `float_exception_flags |= flags;'.
46
47ScottB: November 4, 1998
48Moved this function out of softfloat-specialize into fpmodule.c.
49This effectively isolates all the changes required for integrating with the
50Linux kernel into fpmodule.c. Porting to NetBSD should only require modifying
51fpmodule.c to integrate with the NetBSD kernel (I hope!).
52-------------------------------------------------------------------------------
53void float_raise( int8 flags )
54{
55 float_exception_flags |= flags;
56}
57*/
58
59/*
60-------------------------------------------------------------------------------
61Internal canonical NaN format.
62-------------------------------------------------------------------------------
63*/
64typedef struct {
65 flag sign;
66 bits64 high, low;
67} commonNaNT;
68
69/*
70-------------------------------------------------------------------------------
71The pattern for a default generated single-precision NaN.
72-------------------------------------------------------------------------------
73*/
74#define float32_default_nan 0xFFFFFFFF
75
76/*
77-------------------------------------------------------------------------------
78Returns 1 if the single-precision floating-point value `a' is a NaN;
79otherwise returns 0.
80-------------------------------------------------------------------------------
81*/
82flag float32_is_nan( float32 a )
83{
84
85 return ( 0xFF000000 < (bits32) ( a<<1 ) );
86
87}
88
89/*
90-------------------------------------------------------------------------------
91Returns 1 if the single-precision floating-point value `a' is a signaling
92NaN; otherwise returns 0.
93-------------------------------------------------------------------------------
94*/
95flag float32_is_signaling_nan( float32 a )
96{
97
98 return ( ( ( a>>22 ) & 0x1FF ) == 0x1FE ) && ( a & 0x003FFFFF );
99
100}
101
102/*
103-------------------------------------------------------------------------------
104Returns the result of converting the single-precision floating-point NaN
105`a' to the canonical NaN format. If `a' is a signaling NaN, the invalid
106exception is raised.
107-------------------------------------------------------------------------------
108*/
109static commonNaNT float32ToCommonNaN( float32 a )
110{
111 commonNaNT z;
112
113 if ( float32_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
114 z.sign = a>>31;
115 z.low = 0;
116 z.high = ( (bits64) a )<<41;
117 return z;
118
119}
120
121/*
122-------------------------------------------------------------------------------
123Returns the result of converting the canonical NaN `a' to the single-
124precision floating-point format.
125-------------------------------------------------------------------------------
126*/
127static float32 commonNaNToFloat32( commonNaNT a )
128{
129
130 return ( ( (bits32) a.sign )<<31 ) | 0x7FC00000 | ( a.high>>41 );
131
132}
133
134/*
135-------------------------------------------------------------------------------
136Takes two single-precision floating-point values `a' and `b', one of which
137is a NaN, and returns the appropriate NaN result. If either `a' or `b' is a
138signaling NaN, the invalid exception is raised.
139-------------------------------------------------------------------------------
140*/
141static float32 propagateFloat32NaN( float32 a, float32 b )
142{
143 flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
144
145 aIsNaN = float32_is_nan( a );
146 aIsSignalingNaN = float32_is_signaling_nan( a );
147 bIsNaN = float32_is_nan( b );
148 bIsSignalingNaN = float32_is_signaling_nan( b );
149 a |= 0x00400000;
150 b |= 0x00400000;
151 if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
152 if ( aIsNaN ) {
153 return ( aIsSignalingNaN & bIsNaN ) ? b : a;
154 }
155 else {
156 return b;
157 }
158
159}
160
161/*
162-------------------------------------------------------------------------------
163The pattern for a default generated double-precision NaN.
164-------------------------------------------------------------------------------
165*/
166#define float64_default_nan LIT64( 0xFFFFFFFFFFFFFFFF )
167
168/*
169-------------------------------------------------------------------------------
170Returns 1 if the double-precision floating-point value `a' is a NaN;
171otherwise returns 0.
172-------------------------------------------------------------------------------
173*/
174flag float64_is_nan( float64 a )
175{
176
177 return ( LIT64( 0xFFE0000000000000 ) < (bits64) ( a<<1 ) );
178
179}
180
181/*
182-------------------------------------------------------------------------------
183Returns 1 if the double-precision floating-point value `a' is a signaling
184NaN; otherwise returns 0.
185-------------------------------------------------------------------------------
186*/
187flag float64_is_signaling_nan( float64 a )
188{
189
190 return
191 ( ( ( a>>51 ) & 0xFFF ) == 0xFFE )
192 && ( a & LIT64( 0x0007FFFFFFFFFFFF ) );
193
194}
195
196/*
197-------------------------------------------------------------------------------
198Returns the result of converting the double-precision floating-point NaN
199`a' to the canonical NaN format. If `a' is a signaling NaN, the invalid
200exception is raised.
201-------------------------------------------------------------------------------
202*/
203static commonNaNT float64ToCommonNaN( float64 a )
204{
205 commonNaNT z;
206
207 if ( float64_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
208 z.sign = a>>63;
209 z.low = 0;
210 z.high = a<<12;
211 return z;
212
213}
214
215/*
216-------------------------------------------------------------------------------
217Returns the result of converting the canonical NaN `a' to the double-
218precision floating-point format.
219-------------------------------------------------------------------------------
220*/
221static float64 commonNaNToFloat64( commonNaNT a )
222{
223
224 return
225 ( ( (bits64) a.sign )<<63 )
226 | LIT64( 0x7FF8000000000000 )
227 | ( a.high>>12 );
228
229}
230
231/*
232-------------------------------------------------------------------------------
233Takes two double-precision floating-point values `a' and `b', one of which
234is a NaN, and returns the appropriate NaN result. If either `a' or `b' is a
235signaling NaN, the invalid exception is raised.
236-------------------------------------------------------------------------------
237*/
238static float64 propagateFloat64NaN( float64 a, float64 b )
239{
240 flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
241
242 aIsNaN = float64_is_nan( a );
243 aIsSignalingNaN = float64_is_signaling_nan( a );
244 bIsNaN = float64_is_nan( b );
245 bIsSignalingNaN = float64_is_signaling_nan( b );
246 a |= LIT64( 0x0008000000000000 );
247 b |= LIT64( 0x0008000000000000 );
248 if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
249 if ( aIsNaN ) {
250 return ( aIsSignalingNaN & bIsNaN ) ? b : a;
251 }
252 else {
253 return b;
254 }
255
256}
257
258#ifdef FLOATX80
259
260/*
261-------------------------------------------------------------------------------
262The pattern for a default generated extended double-precision NaN. The
263`high' and `low' values hold the most- and least-significant bits,
264respectively.
265-------------------------------------------------------------------------------
266*/
267#define floatx80_default_nan_high 0xFFFF
268#define floatx80_default_nan_low LIT64( 0xFFFFFFFFFFFFFFFF )
269
270/*
271-------------------------------------------------------------------------------
272Returns 1 if the extended double-precision floating-point value `a' is a
273NaN; otherwise returns 0.
274-------------------------------------------------------------------------------
275*/
276flag floatx80_is_nan( floatx80 a )
277{
278
279 return ( ( a.high & 0x7FFF ) == 0x7FFF ) && (bits64) ( a.low<<1 );
280
281}
282
283/*
284-------------------------------------------------------------------------------
285Returns 1 if the extended double-precision floating-point value `a' is a
286signaling NaN; otherwise returns 0.
287-------------------------------------------------------------------------------
288*/
289flag floatx80_is_signaling_nan( floatx80 a )
290{
291 //register int lr;
292 bits64 aLow;
293
294 //__asm__("mov %0, lr" : : "g" (lr));
295 //fp_printk("floatx80_is_signalling_nan() called from 0x%08x\n",lr);
296 aLow = a.low & ~ LIT64( 0x4000000000000000 );
297 return
298 ( ( a.high & 0x7FFF ) == 0x7FFF )
299 && (bits64) ( aLow<<1 )
300 && ( a.low == aLow );
301
302}
303
304/*
305-------------------------------------------------------------------------------
306Returns the result of converting the extended double-precision floating-
307point NaN `a' to the canonical NaN format. If `a' is a signaling NaN, the
308invalid exception is raised.
309-------------------------------------------------------------------------------
310*/
311static commonNaNT floatx80ToCommonNaN( floatx80 a )
312{
313 commonNaNT z;
314
315 if ( floatx80_is_signaling_nan( a ) ) float_raise( float_flag_invalid );
316 z.sign = a.high>>15;
317 z.low = 0;
318 z.high = a.low<<1;
319 return z;
320
321}
322
323/*
324-------------------------------------------------------------------------------
325Returns the result of converting the canonical NaN `a' to the extended
326double-precision floating-point format.
327-------------------------------------------------------------------------------
328*/
329static floatx80 commonNaNToFloatx80( commonNaNT a )
330{
331 floatx80 z;
332
333 z.low = LIT64( 0xC000000000000000 ) | ( a.high>>1 );
334 z.high = ( ( (bits16) a.sign )<<15 ) | 0x7FFF;
335 return z;
336
337}
338
339/*
340-------------------------------------------------------------------------------
341Takes two extended double-precision floating-point values `a' and `b', one
342of which is a NaN, and returns the appropriate NaN result. If either `a' or
343`b' is a signaling NaN, the invalid exception is raised.
344-------------------------------------------------------------------------------
345*/
346static floatx80 propagateFloatx80NaN( floatx80 a, floatx80 b )
347{
348 flag aIsNaN, aIsSignalingNaN, bIsNaN, bIsSignalingNaN;
349
350 aIsNaN = floatx80_is_nan( a );
351 aIsSignalingNaN = floatx80_is_signaling_nan( a );
352 bIsNaN = floatx80_is_nan( b );
353 bIsSignalingNaN = floatx80_is_signaling_nan( b );
354 a.low |= LIT64( 0xC000000000000000 );
355 b.low |= LIT64( 0xC000000000000000 );
356 if ( aIsSignalingNaN | bIsSignalingNaN ) float_raise( float_flag_invalid );
357 if ( aIsNaN ) {
358 return ( aIsSignalingNaN & bIsNaN ) ? b : a;
359 }
360 else {
361 return b;
362 }
363
364}
365
366#endif