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/* $Id: urem.S,v 1.1.1.1 2001-09-10 07:44:03 simons Exp $
 * urem.S:      This routine was taken from glibc-1.09 and is covered
 *              by the GNU Library General Public License Version 2.
 */
 
/* This file is generated from divrem.m4; DO NOT EDIT! */
/*
 * Division and remainder, from Appendix E of the Sparc Version 8
 * Architecture Manual, with fixes from Gordon Irlam.
 */
 
/*
 * Input: dividend and divisor in %o0 and %o1 respectively.
 *
 * m4 parameters:
 *  .urem       name of function to generate
 *  rem         rem=div => %o0 / %o1; rem=rem => %o0 % %o1
 *  false               false=true => signed; false=false => unsigned
 *
 * Algorithm parameters:
 *  N           how many bits per iteration we try to get (4)
 *  WORDSIZE    total number of bits (32)
 *
 * Derived constants:
 *  TOPBITS     number of bits in the top decade of a number
 *
 * Important variables:
 *  Q           the partial quotient under development (initially 0)
 *  R           the remainder so far, initially the dividend
 *  ITER        number of main division loop iterations required;
 *              equal to ceil(log2(quotient) / N).  Note that this
 *              is the log base (2^N) of the quotient.
 *  V           the current comparand, initially divisor*2^(ITER*N-1)
 *
 * Cost:
 *  Current estimate for non-large dividend is
 *      ceil(log2(quotient) / N) * (10 + 7N/2) + C
 *  A large dividend is one greater than 2^(31-TOPBITS) and takes a
 *  different path, as the upper bits of the quotient must be developed
 *  one bit at a time.
 */
 
        .globl .urem
.urem:
 
        ! Ready to divide.  Compute size of quotient; scale comparand.
        orcc    %o1, %g0, %o5
        bne     1f
        mov     %o0, %o3
 
                ! Divide by zero trap.  If it returns, return 0 (about as
                ! wrong as possible, but that is what SunOS does...).
                ta      ST_DIV0
                retl
                clr     %o0
 
1:
        cmp     %o3, %o5                        ! if %o1 exceeds %o0, done
        blu     Lgot_result             ! (and algorithm fails otherwise)
        clr     %o2
        sethi   %hi(1 << (32 - 4 - 1)), %g1
        cmp     %o3, %g1
        blu     Lnot_really_big
        clr     %o4
 
        ! Here the dividend is >= 2**(31-N) or so.  We must be careful here,
        ! as our usual N-at-a-shot divide step will cause overflow and havoc.
        ! The number of bits in the result here is N*ITER+SC, where SC <= N.
        ! Compute ITER in an unorthodox manner: know we need to shift V into
        ! the top decade: so do not even bother to compare to R.
        1:
                cmp     %o5, %g1
                bgeu    3f
                mov     1, %g7
                sll     %o5, 4, %o5
                b       1b
                add     %o4, 1, %o4
 
        ! Now compute %g7.
        2:      addcc   %o5, %o5, %o5
                bcc     Lnot_too_big
                add     %g7, 1, %g7
 
                ! We get here if the %o1 overflowed while shifting.
                ! This means that %o3 has the high-order bit set.
                ! Restore %o5 and subtract from %o3.
                sll     %g1, 4, %g1     ! high order bit
                srl     %o5, 1, %o5             ! rest of %o5
                add     %o5, %g1, %o5
                b       Ldo_single_div
                sub     %g7, 1, %g7
 
        Lnot_too_big:
        3:      cmp     %o5, %o3
                blu     2b
                nop
                be      Ldo_single_div
                nop
        /* NB: these are commented out in the V8-Sparc manual as well */
        /* (I do not understand this) */
        ! %o5 > %o3: went too far: back up 1 step
        !       srl     %o5, 1, %o5
        !       dec     %g7
        ! do single-bit divide steps
        !
        ! We have to be careful here.  We know that %o3 >= %o5, so we can do the
        ! first divide step without thinking.  BUT, the others are conditional,
        ! and are only done if %o3 >= 0.  Because both %o3 and %o5 may have the high-
        ! order bit set in the first step, just falling into the regular
        ! division loop will mess up the first time around.
        ! So we unroll slightly...
        Ldo_single_div:
                subcc   %g7, 1, %g7
                bl      Lend_regular_divide
                nop
                sub     %o3, %o5, %o3
                mov     1, %o2
                b       Lend_single_divloop
                nop
        Lsingle_divloop:
                sll     %o2, 1, %o2
                bl      1f
                srl     %o5, 1, %o5
                ! %o3 >= 0
                sub     %o3, %o5, %o3
                b       2f
                add     %o2, 1, %o2
        1:      ! %o3 < 0
                add     %o3, %o5, %o3
                sub     %o2, 1, %o2
        2:
        Lend_single_divloop:
                subcc   %g7, 1, %g7
                bge     Lsingle_divloop
                tst     %o3
                b,a     Lend_regular_divide
 
Lnot_really_big:
1:
        sll     %o5, 4, %o5
        cmp     %o5, %o3
        bleu    1b
        addcc   %o4, 1, %o4
        be      Lgot_result
        sub     %o4, 1, %o4
 
        tst     %o3     ! set up for initial iteration
Ldivloop:
        sll     %o2, 4, %o2
                ! depth 1, accumulated bits 0
        bl      L.1.16
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 2, accumulated bits 1
        bl      L.2.17
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 3, accumulated bits 3
        bl      L.3.19
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits 7
        bl      L.4.23
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (7*2+1), %o2
 
L.4.23:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (7*2-1), %o2
 
 
L.3.19:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits 5
        bl      L.4.21
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (5*2+1), %o2
 
L.4.21:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (5*2-1), %o2
 
 
 
L.2.17:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 3, accumulated bits 1
        bl      L.3.17
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits 3
        bl      L.4.19
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (3*2+1), %o2
 
L.4.19:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (3*2-1), %o2
 
 
L.3.17:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits 1
        bl      L.4.17
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (1*2+1), %o2
 
L.4.17:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (1*2-1), %o2
 
 
 
 
L.1.16:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 2, accumulated bits -1
        bl      L.2.15
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 3, accumulated bits -1
        bl      L.3.15
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits -1
        bl      L.4.15
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-1*2+1), %o2
 
L.4.15:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-1*2-1), %o2
 
 
L.3.15:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits -3
        bl      L.4.13
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-3*2+1), %o2
 
L.4.13:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-3*2-1), %o2
 
 
 
L.2.15:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 3, accumulated bits -3
        bl      L.3.13
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits -5
        bl      L.4.11
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-5*2+1), %o2
 
L.4.11:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-5*2-1), %o2
 
 
L.3.13:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits -7
        bl      L.4.9
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-7*2+1), %o2
 
L.4.9:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-7*2-1), %o2
 
 
 
 
        9:
Lend_regular_divide:
        subcc   %o4, 1, %o4
        bge     Ldivloop
        tst     %o3
        bl,a    Lgot_result
        ! non-restoring fixup here (one instruction only!)
        add     %o3, %o1, %o3
 
 
Lgot_result:
 
        retl
        mov %o3, %o0

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[/] [or1k/] [trunk/] [uclinux/] [uClinux-2.0.x/] [arch/] [sparc/] [lib/] [urem.S] - Blame information for rev 1781

Line No.	Rev	Author	Line
1	199	simons	`/* $Id: urem.S,v 1.1.1.1 2001-09-10 07:44:03 simons Exp $`
2			`* urem.S: This routine was taken from glibc-1.09 and is covered`
3			`* by the GNU Library General Public License Version 2.`
4			`*/`
5
6			`/* This file is generated from divrem.m4; DO NOT EDIT! */`
7			`/*`
8			`* Division and remainder, from Appendix E of the Sparc Version 8`
9			`* Architecture Manual, with fixes from Gordon Irlam.`
10			`*/`
11
12			`/*`
13			`* Input: dividend and divisor in %o0 and %o1 respectively.`
14			`*`
15			`* m4 parameters:`
16			`* .urem name of function to generate`
17			`* rem rem=div => %o0 / %o1; rem=rem => %o0 % %o1`
18			`* false false=true => signed; false=false => unsigned`
19			`*`
20			`* Algorithm parameters:`
21			`* N how many bits per iteration we try to get (4)`
22			`* WORDSIZE total number of bits (32)`
23			`*`
24			`* Derived constants:`
25			`* TOPBITS number of bits in the top decade of a number`
26			`*`
27			`* Important variables:`
28			`* Q the partial quotient under development (initially 0)`
29			`* R the remainder so far, initially the dividend`
30			`* ITER number of main division loop iterations required;`
31			`* equal to ceil(log2(quotient) / N). Note that this`
32			`* is the log base (2^N) of the quotient.`
33			`* V the current comparand, initially divisor2^(ITERN-1)`
34			`*`
35			`* Cost:`
36			`* Current estimate for non-large dividend is`
37			`* ceil(log2(quotient) / N) * (10 + 7N/2) + C`
38			`* A large dividend is one greater than 2^(31-TOPBITS) and takes a`
39			`* different path, as the upper bits of the quotient must be developed`
40			`* one bit at a time.`
41			`*/`
42
43			`.globl .urem`
44			`.urem:`
45
46			`! Ready to divide. Compute size of quotient; scale comparand.`
47			`orcc %o1, %g0, %o5`
48			`bne 1f`
49			`mov %o0, %o3`
50
51			`! Divide by zero trap. If it returns, return 0 (about as`
52			`! wrong as possible, but that is what SunOS does...).`
53			`ta ST_DIV0`
54			`retl`
55			`clr %o0`
56
57			`1:`
58			`cmp %o3, %o5 ! if %o1 exceeds %o0, done`
59			`blu Lgot_result ! (and algorithm fails otherwise)`
60			`clr %o2`
61			`sethi %hi(1 << (32 - 4 - 1)), %g1`
62			`cmp %o3, %g1`
63			`blu Lnot_really_big`
64			`clr %o4`
65
66			`! Here the dividend is >= 2**(31-N) or so. We must be careful here,`
67			`! as our usual N-at-a-shot divide step will cause overflow and havoc.`
68			`! The number of bits in the result here is N*ITER+SC, where SC <= N.`
69			`! Compute ITER in an unorthodox manner: know we need to shift V into`
70			`! the top decade: so do not even bother to compare to R.`
71			`1:`
72			`cmp %o5, %g1`
73			`bgeu 3f`
74			`mov 1, %g7`
75			`sll %o5, 4, %o5`
76			`b 1b`
77			`add %o4, 1, %o4`
78
79			`! Now compute %g7.`
80			`2: addcc %o5, %o5, %o5`
81			`bcc Lnot_too_big`
82			`add %g7, 1, %g7`
83
84			`! We get here if the %o1 overflowed while shifting.`
85			`! This means that %o3 has the high-order bit set.`
86			`! Restore %o5 and subtract from %o3.`
87			`sll %g1, 4, %g1 ! high order bit`
88			`srl %o5, 1, %o5 ! rest of %o5`
89			`add %o5, %g1, %o5`
90			`b Ldo_single_div`
91			`sub %g7, 1, %g7`
92
93			`Lnot_too_big:`
94			`3: cmp %o5, %o3`
95			`blu 2b`
96			`nop`
97			`be Ldo_single_div`
98			`nop`
99			`/* NB: these are commented out in the V8-Sparc manual as well */`
100			`/* (I do not understand this) */`
101			`! %o5 > %o3: went too far: back up 1 step`
102			`! srl %o5, 1, %o5`
103			`! dec %g7`
104			`! do single-bit divide steps`
105			`!`
106			`! We have to be careful here. We know that %o3 >= %o5, so we can do the`
107			`! first divide step without thinking. BUT, the others are conditional,`
108			`! and are only done if %o3 >= 0. Because both %o3 and %o5 may have the high-`
109			`! order bit set in the first step, just falling into the regular`
110			`! division loop will mess up the first time around.`
111			`! So we unroll slightly...`
112			`Ldo_single_div:`
113			`subcc %g7, 1, %g7`
114			`bl Lend_regular_divide`
115			`nop`
116			`sub %o3, %o5, %o3`
117			`mov 1, %o2`
118			`b Lend_single_divloop`
119			`nop`
120			`Lsingle_divloop:`
121			`sll %o2, 1, %o2`
122			`bl 1f`
123			`srl %o5, 1, %o5`
124			`! %o3 >= 0`
125			`sub %o3, %o5, %o3`
126			`b 2f`
127			`add %o2, 1, %o2`
128			`1: ! %o3 < 0`
129			`add %o3, %o5, %o3`
130			`sub %o2, 1, %o2`
131			`2:`
132			`Lend_single_divloop:`
133			`subcc %g7, 1, %g7`
134			`bge Lsingle_divloop`
135			`tst %o3`
136			`b,a Lend_regular_divide`
137
138			`Lnot_really_big:`
139			`1:`
140			`sll %o5, 4, %o5`
141			`cmp %o5, %o3`
142			`bleu 1b`
143			`addcc %o4, 1, %o4`
144			`be Lgot_result`
145			`sub %o4, 1, %o4`
146
147			`tst %o3 ! set up for initial iteration`
148			`Ldivloop:`
149			`sll %o2, 4, %o2`
150			`! depth 1, accumulated bits 0`
151			`bl L.1.16`
152			`srl %o5,1,%o5`
153			`! remainder is positive`
154			`subcc %o3,%o5,%o3`
155			`! depth 2, accumulated bits 1`
156			`bl L.2.17`
157			`srl %o5,1,%o5`
158			`! remainder is positive`
159			`subcc %o3,%o5,%o3`
160			`! depth 3, accumulated bits 3`
161			`bl L.3.19`
162			`srl %o5,1,%o5`
163			`! remainder is positive`
164			`subcc %o3,%o5,%o3`
165			`! depth 4, accumulated bits 7`
166			`bl L.4.23`
167			`srl %o5,1,%o5`
168			`! remainder is positive`
169			`subcc %o3,%o5,%o3`
170			`b 9f`
171			`add %o2, (7*2+1), %o2`
172
173			`L.4.23:`
174			`! remainder is negative`
175			`addcc %o3,%o5,%o3`
176			`b 9f`
177			`add %o2, (7*2-1), %o2`
178
179
180			`L.3.19:`
181			`! remainder is negative`
182			`addcc %o3,%o5,%o3`
183			`! depth 4, accumulated bits 5`
184			`bl L.4.21`
185			`srl %o5,1,%o5`
186			`! remainder is positive`
187			`subcc %o3,%o5,%o3`
188			`b 9f`
189			`add %o2, (5*2+1), %o2`
190
191			`L.4.21:`
192			`! remainder is negative`
193			`addcc %o3,%o5,%o3`
194			`b 9f`
195			`add %o2, (5*2-1), %o2`
196
197
198
199			`L.2.17:`
200			`! remainder is negative`
201			`addcc %o3,%o5,%o3`
202			`! depth 3, accumulated bits 1`
203			`bl L.3.17`
204			`srl %o5,1,%o5`
205			`! remainder is positive`
206			`subcc %o3,%o5,%o3`
207			`! depth 4, accumulated bits 3`
208			`bl L.4.19`
209			`srl %o5,1,%o5`
210			`! remainder is positive`
211			`subcc %o3,%o5,%o3`
212			`b 9f`
213			`add %o2, (3*2+1), %o2`
214
215			`L.4.19:`
216			`! remainder is negative`
217			`addcc %o3,%o5,%o3`
218			`b 9f`
219			`add %o2, (3*2-1), %o2`
220
221
222			`L.3.17:`
223			`! remainder is negative`
224			`addcc %o3,%o5,%o3`
225			`! depth 4, accumulated bits 1`
226			`bl L.4.17`
227			`srl %o5,1,%o5`
228			`! remainder is positive`
229			`subcc %o3,%o5,%o3`
230			`b 9f`
231			`add %o2, (1*2+1), %o2`
232
233			`L.4.17:`
234			`! remainder is negative`
235			`addcc %o3,%o5,%o3`
236			`b 9f`
237			`add %o2, (1*2-1), %o2`
238
239
240
241
242			`L.1.16:`
243			`! remainder is negative`
244			`addcc %o3,%o5,%o3`
245			`! depth 2, accumulated bits -1`
246			`bl L.2.15`
247			`srl %o5,1,%o5`
248			`! remainder is positive`
249			`subcc %o3,%o5,%o3`
250			`! depth 3, accumulated bits -1`
251			`bl L.3.15`
252			`srl %o5,1,%o5`
253			`! remainder is positive`
254			`subcc %o3,%o5,%o3`
255			`! depth 4, accumulated bits -1`
256			`bl L.4.15`
257			`srl %o5,1,%o5`
258			`! remainder is positive`
259			`subcc %o3,%o5,%o3`
260			`b 9f`
261			`add %o2, (-1*2+1), %o2`
262
263			`L.4.15:`
264			`! remainder is negative`
265			`addcc %o3,%o5,%o3`
266			`b 9f`
267			`add %o2, (-1*2-1), %o2`
268
269
270			`L.3.15:`
271			`! remainder is negative`
272			`addcc %o3,%o5,%o3`
273			`! depth 4, accumulated bits -3`
274			`bl L.4.13`
275			`srl %o5,1,%o5`
276			`! remainder is positive`
277			`subcc %o3,%o5,%o3`
278			`b 9f`
279			`add %o2, (-3*2+1), %o2`
280
281			`L.4.13:`
282			`! remainder is negative`
283			`addcc %o3,%o5,%o3`
284			`b 9f`
285			`add %o2, (-3*2-1), %o2`
286
287
288
289			`L.2.15:`
290			`! remainder is negative`
291			`addcc %o3,%o5,%o3`
292			`! depth 3, accumulated bits -3`
293			`bl L.3.13`
294			`srl %o5,1,%o5`
295			`! remainder is positive`
296			`subcc %o3,%o5,%o3`
297			`! depth 4, accumulated bits -5`
298			`bl L.4.11`
299			`srl %o5,1,%o5`
300			`! remainder is positive`
301			`subcc %o3,%o5,%o3`
302			`b 9f`
303			`add %o2, (-5*2+1), %o2`
304
305			`L.4.11:`
306			`! remainder is negative`
307			`addcc %o3,%o5,%o3`
308			`b 9f`
309			`add %o2, (-5*2-1), %o2`
310
311
312			`L.3.13:`
313			`! remainder is negative`
314			`addcc %o3,%o5,%o3`
315			`! depth 4, accumulated bits -7`
316			`bl L.4.9`
317			`srl %o5,1,%o5`
318			`! remainder is positive`
319			`subcc %o3,%o5,%o3`
320			`b 9f`
321			`add %o2, (-7*2+1), %o2`
322
323			`L.4.9:`
324			`! remainder is negative`
325			`addcc %o3,%o5,%o3`
326			`b 9f`
327			`add %o2, (-7*2-1), %o2`
328
329
330
331
332			`9:`
333			`Lend_regular_divide:`
334			`subcc %o4, 1, %o4`
335			`bge Ldivloop`
336			`tst %o3`
337			`bl,a Lgot_result`
338			`! non-restoring fixup here (one instruction only!)`
339			`add %o3, %o1, %o3`
340
341
342			`Lgot_result:`
343
344			`retl`
345			`mov %o3, %o0`