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//
2
//      $Id: stwotox.S,v 1.2 2001-09-27 12:01:22 chris Exp $
3
//
4
//      stwotox.sa 3.1 12/10/90
5
//
6
//      stwotox  --- 2**X
7
//      stwotoxd --- 2**X for denormalized X
8
//      stentox  --- 10**X
9
//      stentoxd --- 10**X for denormalized X
10
//
11
//      Input: Double-extended number X in location pointed to
12
//              by address register a0.
13
//
14
//      Output: The function values are returned in Fp0.
15
//
16
//      Accuracy and Monotonicity: The returned result is within 2 ulps in
17
//              64 significant bit, i.e. within 0.5001 ulp to 53 bits if the
18
//              result is subsequently rounded to double precision. The
19
//              result is provably monotonic in double precision.
20
//
21
//      Speed: The program stwotox takes approximately 190 cycles and the
22
//              program stentox takes approximately 200 cycles.
23
//
24
//      Algorithm:
25
//
26
//      twotox
27
//      1. If |X| > 16480, go to ExpBig.
28
//
29
//      2. If |X| < 2**(-70), go to ExpSm.
30
//
31
//      3. Decompose X as X = N/64 + r where |r| <= 1/128. Furthermore
32
//              decompose N as
33
//               N = 64(M + M') + j,  j = 0,1,2,...,63.
34
//
35
//      4. Overwrite r := r * log2. Then
36
//              2**X = 2**(M') * 2**(M) * 2**(j/64) * exp(r).
37
//              Go to expr to compute that expression.
38
//
39
//      tentox
40
//      1. If |X| > 16480*log_10(2) (base 10 log of 2), go to ExpBig.
41
//
42
//      2. If |X| < 2**(-70), go to ExpSm.
43
//
44
//      3. Set y := X*log_2(10)*64 (base 2 log of 10). Set
45
//              N := round-to-int(y). Decompose N as
46
//               N = 64(M + M') + j,  j = 0,1,2,...,63.
47
//
48
//      4. Define r as
49
//              r := ((X - N*L1)-N*L2) * L10
50
//              where L1, L2 are the leading and trailing parts of log_10(2)/64
51
//              and L10 is the natural log of 10. Then
52
//              10**X = 2**(M') * 2**(M) * 2**(j/64) * exp(r).
53
//              Go to expr to compute that expression.
54
//
55
//      expr
56
//      1. Fetch 2**(j/64) from table as Fact1 and Fact2.
57
//
58
//      2. Overwrite Fact1 and Fact2 by
59
//              Fact1 := 2**(M) * Fact1
60
//              Fact2 := 2**(M) * Fact2
61
//              Thus Fact1 + Fact2 = 2**(M) * 2**(j/64).
62
//
63
//      3. Calculate P where 1 + P approximates exp(r):
64
//              P = r + r*r*(A1+r*(A2+...+r*A5)).
65
//
66
//      4. Let AdjFact := 2**(M'). Return
67
//              AdjFact * ( Fact1 + ((Fact1*P) + Fact2) ).
68
//              Exit.
69
//
70
//      ExpBig
71
//      1. Generate overflow by Huge * Huge if X > 0; otherwise, generate
72
//              underflow by Tiny * Tiny.
73
//
74
//      ExpSm
75
//      1. Return 1 + X.
76
//
77
 
78
//              Copyright (C) Motorola, Inc. 1990
79
//                      All Rights Reserved
80
//
81
//      THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
82
//      The copyright notice above does not evidence any
83
//      actual or intended publication of such source code.
84
 
85
//STWOTOX       idnt    2,1 | Motorola 040 Floating Point Software Package
86
 
87
        |section        8
88
 
89
#include "fpsp.defs"
90
 
91
BOUNDS1:        .long 0x3FB98000,0x400D80C0 // ... 2^(-70),16480
92
BOUNDS2:        .long 0x3FB98000,0x400B9B07 // ... 2^(-70),16480 LOG2/LOG10
93
 
94
L2TEN64:        .long 0x406A934F,0x0979A371 // ... 64LOG10/LOG2
95
L10TWO1:        .long 0x3F734413,0x509F8000 // ... LOG2/64LOG10
96
 
97
L10TWO2:        .long 0xBFCD0000,0xC0219DC1,0xDA994FD2,0x00000000
98
 
99
LOG10:  .long 0x40000000,0x935D8DDD,0xAAA8AC17,0x00000000
100
 
101
LOG2:   .long 0x3FFE0000,0xB17217F7,0xD1CF79AC,0x00000000
102
 
103
EXPA5:  .long 0x3F56C16D,0x6F7BD0B2
104
EXPA4:  .long 0x3F811112,0x302C712C
105
EXPA3:  .long 0x3FA55555,0x55554CC1
106
EXPA2:  .long 0x3FC55555,0x55554A54
107
EXPA1:  .long 0x3FE00000,0x00000000,0x00000000,0x00000000
108
 
109
HUGE:   .long 0x7FFE0000,0xFFFFFFFF,0xFFFFFFFF,0x00000000
110
TINY:   .long 0x00010000,0xFFFFFFFF,0xFFFFFFFF,0x00000000
111
 
112
EXPTBL:
113
        .long  0x3FFF0000,0x80000000,0x00000000,0x3F738000
114
        .long  0x3FFF0000,0x8164D1F3,0xBC030773,0x3FBEF7CA
115
        .long  0x3FFF0000,0x82CD8698,0xAC2BA1D7,0x3FBDF8A9
116
        .long  0x3FFF0000,0x843A28C3,0xACDE4046,0x3FBCD7C9
117
        .long  0x3FFF0000,0x85AAC367,0xCC487B15,0xBFBDE8DA
118
        .long  0x3FFF0000,0x871F6196,0x9E8D1010,0x3FBDE85C
119
        .long  0x3FFF0000,0x88980E80,0x92DA8527,0x3FBEBBF1
120
        .long  0x3FFF0000,0x8A14D575,0x496EFD9A,0x3FBB80CA
121
        .long  0x3FFF0000,0x8B95C1E3,0xEA8BD6E7,0xBFBA8373
122
        .long  0x3FFF0000,0x8D1ADF5B,0x7E5BA9E6,0xBFBE9670
123
        .long  0x3FFF0000,0x8EA4398B,0x45CD53C0,0x3FBDB700
124
        .long  0x3FFF0000,0x9031DC43,0x1466B1DC,0x3FBEEEB0
125
        .long  0x3FFF0000,0x91C3D373,0xAB11C336,0x3FBBFD6D
126
        .long  0x3FFF0000,0x935A2B2F,0x13E6E92C,0xBFBDB319
127
        .long  0x3FFF0000,0x94F4EFA8,0xFEF70961,0x3FBDBA2B
128
        .long  0x3FFF0000,0x96942D37,0x20185A00,0x3FBE91D5
129
        .long  0x3FFF0000,0x9837F051,0x8DB8A96F,0x3FBE8D5A
130
        .long  0x3FFF0000,0x99E04593,0x20B7FA65,0xBFBCDE7B
131
        .long  0x3FFF0000,0x9B8D39B9,0xD54E5539,0xBFBEBAAF
132
        .long  0x3FFF0000,0x9D3ED9A7,0x2CFFB751,0xBFBD86DA
133
        .long  0x3FFF0000,0x9EF53260,0x91A111AE,0xBFBEBEDD
134
        .long  0x3FFF0000,0xA0B0510F,0xB9714FC2,0x3FBCC96E
135
        .long  0x3FFF0000,0xA2704303,0x0C496819,0xBFBEC90B
136
        .long  0x3FFF0000,0xA43515AE,0x09E6809E,0x3FBBD1DB
137
        .long  0x3FFF0000,0xA5FED6A9,0xB15138EA,0x3FBCE5EB
138
        .long  0x3FFF0000,0xA7CD93B4,0xE965356A,0xBFBEC274
139
        .long  0x3FFF0000,0xA9A15AB4,0xEA7C0EF8,0x3FBEA83C
140
        .long  0x3FFF0000,0xAB7A39B5,0xA93ED337,0x3FBECB00
141
        .long  0x3FFF0000,0xAD583EEA,0x42A14AC6,0x3FBE9301
142
        .long  0x3FFF0000,0xAF3B78AD,0x690A4375,0xBFBD8367
143
        .long  0x3FFF0000,0xB123F581,0xD2AC2590,0xBFBEF05F
144
        .long  0x3FFF0000,0xB311C412,0xA9112489,0x3FBDFB3C
145
        .long  0x3FFF0000,0xB504F333,0xF9DE6484,0x3FBEB2FB
146
        .long  0x3FFF0000,0xB6FD91E3,0x28D17791,0x3FBAE2CB
147
        .long  0x3FFF0000,0xB8FBAF47,0x62FB9EE9,0x3FBCDC3C
148
        .long  0x3FFF0000,0xBAFF5AB2,0x133E45FB,0x3FBEE9AA
149
        .long  0x3FFF0000,0xBD08A39F,0x580C36BF,0xBFBEAEFD
150
        .long  0x3FFF0000,0xBF1799B6,0x7A731083,0xBFBCBF51
151
        .long  0x3FFF0000,0xC12C4CCA,0x66709456,0x3FBEF88A
152
        .long  0x3FFF0000,0xC346CCDA,0x24976407,0x3FBD83B2
153
        .long  0x3FFF0000,0xC5672A11,0x5506DADD,0x3FBDF8AB
154
        .long  0x3FFF0000,0xC78D74C8,0xABB9B15D,0xBFBDFB17
155
        .long  0x3FFF0000,0xC9B9BD86,0x6E2F27A3,0xBFBEFE3C
156
        .long  0x3FFF0000,0xCBEC14FE,0xF2727C5D,0xBFBBB6F8
157
        .long  0x3FFF0000,0xCE248C15,0x1F8480E4,0xBFBCEE53
158
        .long  0x3FFF0000,0xD06333DA,0xEF2B2595,0xBFBDA4AE
159
        .long  0x3FFF0000,0xD2A81D91,0xF12AE45A,0x3FBC9124
160
        .long  0x3FFF0000,0xD4F35AAB,0xCFEDFA1F,0x3FBEB243
161
        .long  0x3FFF0000,0xD744FCCA,0xD69D6AF4,0x3FBDE69A
162
        .long  0x3FFF0000,0xD99D15C2,0x78AFD7B6,0xBFB8BC61
163
        .long  0x3FFF0000,0xDBFBB797,0xDAF23755,0x3FBDF610
164
        .long  0x3FFF0000,0xDE60F482,0x5E0E9124,0xBFBD8BE1
165
        .long  0x3FFF0000,0xE0CCDEEC,0x2A94E111,0x3FBACB12
166
        .long  0x3FFF0000,0xE33F8972,0xBE8A5A51,0x3FBB9BFE
167
        .long  0x3FFF0000,0xE5B906E7,0x7C8348A8,0x3FBCF2F4
168
        .long  0x3FFF0000,0xE8396A50,0x3C4BDC68,0x3FBEF22F
169
        .long  0x3FFF0000,0xEAC0C6E7,0xDD24392F,0xBFBDBF4A
170
        .long  0x3FFF0000,0xED4F301E,0xD9942B84,0x3FBEC01A
171
        .long  0x3FFF0000,0xEFE4B99B,0xDCDAF5CB,0x3FBE8CAC
172
        .long  0x3FFF0000,0xF281773C,0x59FFB13A,0xBFBCBB3F
173
        .long  0x3FFF0000,0xF5257D15,0x2486CC2C,0x3FBEF73A
174
        .long  0x3FFF0000,0xF7D0DF73,0x0AD13BB9,0xBFB8B795
175
        .long  0x3FFF0000,0xFA83B2DB,0x722A033A,0x3FBEF84B
176
        .long  0x3FFF0000,0xFD3E0C0C,0xF486C175,0xBFBEF581
177
 
178
        .set    N,L_SCR1
179
 
180
        .set    X,FP_SCR1
181
        .set    XDCARE,X+2
182
        .set    XFRAC,X+4
183
 
184
        .set    ADJFACT,FP_SCR2
185
 
186
        .set    FACT1,FP_SCR3
187
        .set    FACT1HI,FACT1+4
188
        .set    FACT1LOW,FACT1+8
189
 
190
        .set    FACT2,FP_SCR4
191
        .set    FACT2HI,FACT2+4
192
        .set    FACT2LOW,FACT2+8
193
 
194
        | xref  t_unfl
195
        |xref   t_ovfl
196
        |xref   t_frcinx
197
 
198
        .global stwotoxd
199
stwotoxd:
200
//--ENTRY POINT FOR 2**(X) FOR DENORMALIZED ARGUMENT
201
 
202
        fmovel          %d1,%fpcr               // ...set user's rounding mode/precision
203
        fmoves          #0x3F800000,%fp0  // ...RETURN 1 + X
204
        movel           (%a0),%d0
205
        orl             #0x00800001,%d0
206
        fadds           %d0,%fp0
207
        bra             t_frcinx
208
 
209
        .global stwotox
210
stwotox:
211
//--ENTRY POINT FOR 2**(X), HERE X IS FINITE, NON-ZERO, AND NOT NAN'S
212
        fmovemx (%a0),%fp0-%fp0 // ...LOAD INPUT, do not set cc's
213
 
214
        movel           (%a0),%d0
215
        movew           4(%a0),%d0
216
        fmovex          %fp0,X(%a6)
217
        andil           #0x7FFFFFFF,%d0
218
 
219
        cmpil           #0x3FB98000,%d0         // ...|X| >= 2**(-70)?
220
        bges            TWOOK1
221
        bra             EXPBORS
222
 
223
TWOOK1:
224
        cmpil           #0x400D80C0,%d0         // ...|X| > 16480?
225
        bles            TWOMAIN
226
        bra             EXPBORS
227
 
228
 
229
TWOMAIN:
230
//--USUAL CASE, 2^(-70) <= |X| <= 16480
231
 
232
        fmovex          %fp0,%fp1
233
        fmuls           #0x42800000,%fp1  // ...64 * X
234
 
235
        fmovel          %fp1,N(%a6)             // ...N = ROUND-TO-INT(64 X)
236
        movel           %d2,-(%sp)
237
        lea             EXPTBL,%a1      // ...LOAD ADDRESS OF TABLE OF 2^(J/64)
238
        fmovel          N(%a6),%fp1             // ...N --> FLOATING FMT
239
        movel           N(%a6),%d0
240
        movel           %d0,%d2
241
        andil           #0x3F,%d0               // ...D0 IS J
242
        asll            #4,%d0          // ...DISPLACEMENT FOR 2^(J/64)
243
        addal           %d0,%a1         // ...ADDRESS FOR 2^(J/64)
244
        asrl            #6,%d2          // ...d2 IS L, N = 64L + J
245
        movel           %d2,%d0
246
        asrl            #1,%d0          // ...D0 IS M
247
        subl            %d0,%d2         // ...d2 IS M', N = 64(M+M') + J
248
        addil           #0x3FFF,%d2
249
        movew           %d2,ADJFACT(%a6)        // ...ADJFACT IS 2^(M')
250
        movel           (%sp)+,%d2
251
//--SUMMARY: a1 IS ADDRESS FOR THE LEADING PORTION OF 2^(J/64),
252
//--D0 IS M WHERE N = 64(M+M') + J. NOTE THAT |M| <= 16140 BY DESIGN.
253
//--ADJFACT = 2^(M').
254
//--REGISTERS SAVED SO FAR ARE (IN ORDER) FPCR, D0, FP1, a1, AND FP2.
255
 
256
        fmuls           #0x3C800000,%fp1  // ...(1/64)*N
257
        movel           (%a1)+,FACT1(%a6)
258
        movel           (%a1)+,FACT1HI(%a6)
259
        movel           (%a1)+,FACT1LOW(%a6)
260
        movew           (%a1)+,FACT2(%a6)
261
        clrw            FACT2+2(%a6)
262
 
263
        fsubx           %fp1,%fp0               // ...X - (1/64)*INT(64 X)
264
 
265
        movew           (%a1)+,FACT2HI(%a6)
266
        clrw            FACT2HI+2(%a6)
267
        clrl            FACT2LOW(%a6)
268
        addw            %d0,FACT1(%a6)
269
 
270
        fmulx           LOG2,%fp0       // ...FP0 IS R
271
        addw            %d0,FACT2(%a6)
272
 
273
        bra             expr
274
 
275
EXPBORS:
276
//--FPCR, D0 SAVED
277
        cmpil           #0x3FFF8000,%d0
278
        bgts            EXPBIG
279
 
280
EXPSM:
281
//--|X| IS SMALL, RETURN 1 + X
282
 
283
        fmovel          %d1,%FPCR               //restore users exceptions
284
        fadds           #0x3F800000,%fp0  // ...RETURN 1 + X
285
 
286
        bra             t_frcinx
287
 
288
EXPBIG:
289
//--|X| IS LARGE, GENERATE OVERFLOW IF X > 0; ELSE GENERATE UNDERFLOW
290
//--REGISTERS SAVE SO FAR ARE FPCR AND  D0
291
        movel           X(%a6),%d0
292
        cmpil           #0,%d0
293
        blts            EXPNEG
294
 
295
        bclrb           #7,(%a0)                //t_ovfl expects positive value
296
        bra             t_ovfl
297
 
298
EXPNEG:
299
        bclrb           #7,(%a0)                //t_unfl expects positive value
300
        bra             t_unfl
301
 
302
        .global stentoxd
303
stentoxd:
304
//--ENTRY POINT FOR 10**(X) FOR DENORMALIZED ARGUMENT
305
 
306
        fmovel          %d1,%fpcr               // ...set user's rounding mode/precision
307
        fmoves          #0x3F800000,%fp0  // ...RETURN 1 + X
308
        movel           (%a0),%d0
309
        orl             #0x00800001,%d0
310
        fadds           %d0,%fp0
311
        bra             t_frcinx
312
 
313
        .global stentox
314
stentox:
315
//--ENTRY POINT FOR 10**(X), HERE X IS FINITE, NON-ZERO, AND NOT NAN'S
316
        fmovemx (%a0),%fp0-%fp0 // ...LOAD INPUT, do not set cc's
317
 
318
        movel           (%a0),%d0
319
        movew           4(%a0),%d0
320
        fmovex          %fp0,X(%a6)
321
        andil           #0x7FFFFFFF,%d0
322
 
323
        cmpil           #0x3FB98000,%d0         // ...|X| >= 2**(-70)?
324
        bges            TENOK1
325
        bra             EXPBORS
326
 
327
TENOK1:
328
        cmpil           #0x400B9B07,%d0         // ...|X| <= 16480*log2/log10 ?
329
        bles            TENMAIN
330
        bra             EXPBORS
331
 
332
TENMAIN:
333
//--USUAL CASE, 2^(-70) <= |X| <= 16480 LOG 2 / LOG 10
334
 
335
        fmovex          %fp0,%fp1
336
        fmuld           L2TEN64,%fp1    // ...X*64*LOG10/LOG2
337
 
338
        fmovel          %fp1,N(%a6)             // ...N=INT(X*64*LOG10/LOG2)
339
        movel           %d2,-(%sp)
340
        lea             EXPTBL,%a1      // ...LOAD ADDRESS OF TABLE OF 2^(J/64)
341
        fmovel          N(%a6),%fp1             // ...N --> FLOATING FMT
342
        movel           N(%a6),%d0
343
        movel           %d0,%d2
344
        andil           #0x3F,%d0               // ...D0 IS J
345
        asll            #4,%d0          // ...DISPLACEMENT FOR 2^(J/64)
346
        addal           %d0,%a1         // ...ADDRESS FOR 2^(J/64)
347
        asrl            #6,%d2          // ...d2 IS L, N = 64L + J
348
        movel           %d2,%d0
349
        asrl            #1,%d0          // ...D0 IS M
350
        subl            %d0,%d2         // ...d2 IS M', N = 64(M+M') + J
351
        addil           #0x3FFF,%d2
352
        movew           %d2,ADJFACT(%a6)        // ...ADJFACT IS 2^(M')
353
        movel           (%sp)+,%d2
354
 
355
//--SUMMARY: a1 IS ADDRESS FOR THE LEADING PORTION OF 2^(J/64),
356
//--D0 IS M WHERE N = 64(M+M') + J. NOTE THAT |M| <= 16140 BY DESIGN.
357
//--ADJFACT = 2^(M').
358
//--REGISTERS SAVED SO FAR ARE (IN ORDER) FPCR, D0, FP1, a1, AND FP2.
359
 
360
        fmovex          %fp1,%fp2
361
 
362
        fmuld           L10TWO1,%fp1    // ...N*(LOG2/64LOG10)_LEAD
363
        movel           (%a1)+,FACT1(%a6)
364
 
365
        fmulx           L10TWO2,%fp2    // ...N*(LOG2/64LOG10)_TRAIL
366
 
367
        movel           (%a1)+,FACT1HI(%a6)
368
        movel           (%a1)+,FACT1LOW(%a6)
369
        fsubx           %fp1,%fp0               // ...X - N L_LEAD
370
        movew           (%a1)+,FACT2(%a6)
371
 
372
        fsubx           %fp2,%fp0               // ...X - N L_TRAIL
373
 
374
        clrw            FACT2+2(%a6)
375
        movew           (%a1)+,FACT2HI(%a6)
376
        clrw            FACT2HI+2(%a6)
377
        clrl            FACT2LOW(%a6)
378
 
379
        fmulx           LOG10,%fp0      // ...FP0 IS R
380
 
381
        addw            %d0,FACT1(%a6)
382
        addw            %d0,FACT2(%a6)
383
 
384
expr:
385
//--FPCR, FP2, FP3 ARE SAVED IN ORDER AS SHOWN.
386
//--ADJFACT CONTAINS 2**(M'), FACT1 + FACT2 = 2**(M) * 2**(J/64).
387
//--FP0 IS R. THE FOLLOWING CODE COMPUTES
388
//--    2**(M'+M) * 2**(J/64) * EXP(R)
389
 
390
        fmovex          %fp0,%fp1
391
        fmulx           %fp1,%fp1               // ...FP1 IS S = R*R
392
 
393
        fmoved          EXPA5,%fp2      // ...FP2 IS A5
394
        fmoved          EXPA4,%fp3      // ...FP3 IS A4
395
 
396
        fmulx           %fp1,%fp2               // ...FP2 IS S*A5
397
        fmulx           %fp1,%fp3               // ...FP3 IS S*A4
398
 
399
        faddd           EXPA3,%fp2      // ...FP2 IS A3+S*A5
400
        faddd           EXPA2,%fp3      // ...FP3 IS A2+S*A4
401
 
402
        fmulx           %fp1,%fp2               // ...FP2 IS S*(A3+S*A5)
403
        fmulx           %fp1,%fp3               // ...FP3 IS S*(A2+S*A4)
404
 
405
        faddd           EXPA1,%fp2      // ...FP2 IS A1+S*(A3+S*A5)
406
        fmulx           %fp0,%fp3               // ...FP3 IS R*S*(A2+S*A4)
407
 
408
        fmulx           %fp1,%fp2               // ...FP2 IS S*(A1+S*(A3+S*A5))
409
        faddx           %fp3,%fp0               // ...FP0 IS R+R*S*(A2+S*A4)
410
 
411
        faddx           %fp2,%fp0               // ...FP0 IS EXP(R) - 1
412
 
413
 
414
//--FINAL RECONSTRUCTION PROCESS
415
//--EXP(X) = 2^M*2^(J/64) + 2^M*2^(J/64)*(EXP(R)-1)  -  (1 OR 0)
416
 
417
        fmulx           FACT1(%a6),%fp0
418
        faddx           FACT2(%a6),%fp0
419
        faddx           FACT1(%a6),%fp0
420
 
421
        fmovel          %d1,%FPCR               //restore users exceptions
422
        clrw            ADJFACT+2(%a6)
423
        movel           #0x80000000,ADJFACT+4(%a6)
424
        clrl            ADJFACT+8(%a6)
425
        fmulx           ADJFACT(%a6),%fp0       // ...FINAL ADJUSTMENT
426
 
427
        bra             t_frcinx
428
 
429
        |end

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