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   /* 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:
 *  .udiv       name of function to generate
 *  div         div=div => %o0 / %o1; div=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.
 */
 
 
 
#include 
 
.global   .udiv;
.align 4;
.type  .udiv ,@function;
 
.udiv:
        ! 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      0x02
                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, %g2
                sll     %o5, 4, %o5
                b       1b
                add     %o4, 1, %o4
 
        ! Now compute %g2.
        2:      addcc   %o5, %o5, %o5
                bcc     .Lnot_too_big
                add     %g2, 1, %g2
 
                ! 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     %g2, 1, %g2
 
        .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     %g2
        ! 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   %g2, 1, %g2
                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   %g2, 1, %g2
                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      .L1.16
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 2, accumulated bits 1
        bl      .L2.17
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 3, accumulated bits 3
        bl      .L3.19
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits 7
        bl      .L4.23
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (7*2+1), %o2
 
.L4.23:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (7*2-1), %o2
 
 
.L3.19:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits 5
        bl      .L4.21
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (5*2+1), %o2
 
.L4.21:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (5*2-1), %o2
 
 
 
.L2.17:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 3, accumulated bits 1
        bl      .L3.17
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits 3
        bl      .L4.19
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (3*2+1), %o2
 
.L4.19:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (3*2-1), %o2
 
 
.L3.17:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits 1
        bl      .L4.17
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (1*2+1), %o2
 
.L4.17:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (1*2-1), %o2
 
 
 
 
.L1.16:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 2, accumulated bits -1
        bl      .L2.15
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 3, accumulated bits -1
        bl      .L3.15
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits -1
        bl      .L4.15
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-1*2+1), %o2
 
.L4.15:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-1*2-1), %o2
 
 
.L3.15:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits -3
        bl      .L4.13
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-3*2+1), %o2
 
.L4.13:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-3*2-1), %o2
 
 
 
.L2.15:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 3, accumulated bits -3
        bl      .L3.13
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits -5
        bl      .L4.11
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-5*2+1), %o2
 
.L4.11:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-5*2-1), %o2
 
 
.L3.13:
        ! remainder is negative
        addcc   %o3,%o5,%o3
                        ! depth 4, accumulated bits -7
        bl      .L4.9
        srl     %o5,1,%o5
        ! remainder is positive
        subcc   %o3,%o5,%o3
                b       9f
                add     %o2, (-7*2+1), %o2
 
.L4.9:
        ! 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!)
        sub     %o2, 1, %o2
 
 
.Lgot_result:
 
        retl
        mov %o2, %o0
 
.size .udiv,.-.udiv;

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[/] [or1k_old/] [trunk/] [linux/] [uClibc/] [libc/] [sysdeps/] [linux/] [sparc/] [udiv.S] - Blame information for rev 1782

Line No.	Rev	Author	Line
1	1325	phoenix	`/* This file is generated from divrem.m4; DO NOT EDIT! */`
2			`/*`
3			`* Division and remainder, from Appendix E of the Sparc Version 8`
4			`* Architecture Manual, with fixes from Gordon Irlam.`
5			`*/`
6
7			`/*`
8			`* Input: dividend and divisor in %o0 and %o1 respectively.`
9			`*`
10			`* m4 parameters:`
11			`* .udiv name of function to generate`
12			`* div div=div => %o0 / %o1; div=rem => %o0 % %o1`
13			`* false false=true => signed; false=false => unsigned`
14			`*`
15			`* Algorithm parameters:`
16			`* N how many bits per iteration we try to get (4)`
17			`* WORDSIZE total number of bits (32)`
18			`*`
19			`* Derived constants:`
20			`* TOPBITS number of bits in the top decade of a number`
21			`*`
22			`* Important variables:`
23			`* Q the partial quotient under development (initially 0)`
24			`* R the remainder so far, initially the dividend`
25			`* ITER number of main division loop iterations required;`
26			`* equal to ceil(log2(quotient) / N). Note that this`
27			`* is the log base (2^N) of the quotient.`
28			`* V the current comparand, initially divisor2^(ITERN-1)`
29			`*`
30			`* Cost:`
31			`* Current estimate for non-large dividend is`
32			`* ceil(log2(quotient) / N) * (10 + 7N/2) + C`
33			`* A large dividend is one greater than 2^(31-TOPBITS) and takes a`
34			`* different path, as the upper bits of the quotient must be developed`
35			`* one bit at a time.`
36			`*/`
37
38
39
40			`#include`
41
42			`.global .udiv;`
43			`.align 4;`
44			`.type .udiv ,@function;`
45
46			`.udiv:`
47			`! Ready to divide. Compute size of quotient; scale comparand.`
48			`orcc %o1, %g0, %o5`
49			`bne 1f`
50			`mov %o0, %o3`
51
52			`! Divide by zero trap. If it returns, return 0 (about as`
53			`! wrong as possible, but that is what SunOS does...).`
54			`ta 0x02`
55			`retl`
56			`clr %o0`
57
58			`1:`
59			`cmp %o3, %o5 ! if %o1 exceeds %o0, done`
60			`blu .Lgot_result ! (and algorithm fails otherwise)`
61			`clr %o2`
62			`sethi %hi(1 << (32 - 4 - 1)), %g1`
63			`cmp %o3, %g1`
64			`blu .Lnot_really_big`
65			`clr %o4`
66
67			`! Here the dividend is >= 2**(31-N) or so. We must be careful here,`
68			`! as our usual N-at-a-shot divide step will cause overflow and havoc.`
69			`! The number of bits in the result here is N*ITER+SC, where SC <= N.`
70			`! Compute ITER in an unorthodox manner: know we need to shift V into`
71			`! the top decade: so do not even bother to compare to R.`
72			`1:`
73			`cmp %o5, %g1`
74			`bgeu 3f`
75			`mov 1, %g2`
76			`sll %o5, 4, %o5`
77			`b 1b`
78			`add %o4, 1, %o4`
79
80			`! Now compute %g2.`
81			`2: addcc %o5, %o5, %o5`
82			`bcc .Lnot_too_big`
83			`add %g2, 1, %g2`
84
85			`! We get here if the %o1 overflowed while shifting.`
86			`! This means that %o3 has the high-order bit set.`
87			`! Restore %o5 and subtract from %o3.`
88			`sll %g1, 4, %g1 ! high order bit`
89			`srl %o5, 1, %o5 ! rest of %o5`
90			`add %o5, %g1, %o5`
91			`b .Ldo_single_div`
92			`sub %g2, 1, %g2`
93
94			`.Lnot_too_big:`
95			`3: cmp %o5, %o3`
96			`blu 2b`
97			`nop`
98			`be .Ldo_single_div`
99			`nop`
100			`/* NB: these are commented out in the V8-Sparc manual as well */`
101			`/* (I do not understand this) */`
102			`! %o5 > %o3: went too far: back up 1 step`
103			`! srl %o5, 1, %o5`
104			`! dec %g2`
105			`! do single-bit divide steps`
106			`!`
107			`! We have to be careful here. We know that %o3 >= %o5, so we can do the`
108			`! first divide step without thinking. BUT, the others are conditional,`
109			`! and are only done if %o3 >= 0. Because both %o3 and %o5 may have the high-`
110			`! order bit set in the first step, just falling into the regular`
111			`! division loop will mess up the first time around.`
112			`! So we unroll slightly...`
113			`.Ldo_single_div:`
114			`subcc %g2, 1, %g2`
115			`bl .Lend_regular_divide`
116			`nop`
117			`sub %o3, %o5, %o3`
118			`mov 1, %o2`
119			`b .Lend_single_divloop`
120			`nop`
121			`.Lsingle_divloop:`
122			`sll %o2, 1, %o2`
123			`bl 1f`
124			`srl %o5, 1, %o5`
125			`! %o3 >= 0`
126			`sub %o3, %o5, %o3`
127			`b 2f`
128			`add %o2, 1, %o2`
129			`1: ! %o3 < 0`
130			`add %o3, %o5, %o3`
131			`sub %o2, 1, %o2`
132			`2:`
133			`.Lend_single_divloop:`
134			`subcc %g2, 1, %g2`
135			`bge .Lsingle_divloop`
136			`tst %o3`
137			`b,a .Lend_regular_divide`
138
139			`.Lnot_really_big:`
140			`1:`
141			`sll %o5, 4, %o5`
142			`cmp %o5, %o3`
143			`bleu 1b`
144			`addcc %o4, 1, %o4`
145			`be .Lgot_result`
146			`sub %o4, 1, %o4`
147
148			`tst %o3 ! set up for initial iteration`
149			`.Ldivloop:`
150			`sll %o2, 4, %o2`
151			`! depth 1, accumulated bits 0`
152			`bl .L1.16`
153			`srl %o5,1,%o5`
154			`! remainder is positive`
155			`subcc %o3,%o5,%o3`
156			`! depth 2, accumulated bits 1`
157			`bl .L2.17`
158			`srl %o5,1,%o5`
159			`! remainder is positive`
160			`subcc %o3,%o5,%o3`
161			`! depth 3, accumulated bits 3`
162			`bl .L3.19`
163			`srl %o5,1,%o5`
164			`! remainder is positive`
165			`subcc %o3,%o5,%o3`
166			`! depth 4, accumulated bits 7`
167			`bl .L4.23`
168			`srl %o5,1,%o5`
169			`! remainder is positive`
170			`subcc %o3,%o5,%o3`
171			`b 9f`
172			`add %o2, (7*2+1), %o2`
173
174			`.L4.23:`
175			`! remainder is negative`
176			`addcc %o3,%o5,%o3`
177			`b 9f`
178			`add %o2, (7*2-1), %o2`
179
180
181			`.L3.19:`
182			`! remainder is negative`
183			`addcc %o3,%o5,%o3`
184			`! depth 4, accumulated bits 5`
185			`bl .L4.21`
186			`srl %o5,1,%o5`
187			`! remainder is positive`
188			`subcc %o3,%o5,%o3`
189			`b 9f`
190			`add %o2, (5*2+1), %o2`
191
192			`.L4.21:`
193			`! remainder is negative`
194			`addcc %o3,%o5,%o3`
195			`b 9f`
196			`add %o2, (5*2-1), %o2`
197
198
199
200			`.L2.17:`
201			`! remainder is negative`
202			`addcc %o3,%o5,%o3`
203			`! depth 3, accumulated bits 1`
204			`bl .L3.17`
205			`srl %o5,1,%o5`
206			`! remainder is positive`
207			`subcc %o3,%o5,%o3`
208			`! depth 4, accumulated bits 3`
209			`bl .L4.19`
210			`srl %o5,1,%o5`
211			`! remainder is positive`
212			`subcc %o3,%o5,%o3`
213			`b 9f`
214			`add %o2, (3*2+1), %o2`
215
216			`.L4.19:`
217			`! remainder is negative`
218			`addcc %o3,%o5,%o3`
219			`b 9f`
220			`add %o2, (3*2-1), %o2`
221
222
223			`.L3.17:`
224			`! remainder is negative`
225			`addcc %o3,%o5,%o3`
226			`! depth 4, accumulated bits 1`
227			`bl .L4.17`
228			`srl %o5,1,%o5`
229			`! remainder is positive`
230			`subcc %o3,%o5,%o3`
231			`b 9f`
232			`add %o2, (1*2+1), %o2`
233
234			`.L4.17:`
235			`! remainder is negative`
236			`addcc %o3,%o5,%o3`
237			`b 9f`
238			`add %o2, (1*2-1), %o2`
239
240
241
242
243			`.L1.16:`
244			`! remainder is negative`
245			`addcc %o3,%o5,%o3`
246			`! depth 2, accumulated bits -1`
247			`bl .L2.15`
248			`srl %o5,1,%o5`
249			`! remainder is positive`
250			`subcc %o3,%o5,%o3`
251			`! depth 3, accumulated bits -1`
252			`bl .L3.15`
253			`srl %o5,1,%o5`
254			`! remainder is positive`
255			`subcc %o3,%o5,%o3`
256			`! depth 4, accumulated bits -1`
257			`bl .L4.15`
258			`srl %o5,1,%o5`
259			`! remainder is positive`
260			`subcc %o3,%o5,%o3`
261			`b 9f`
262			`add %o2, (-1*2+1), %o2`
263
264			`.L4.15:`
265			`! remainder is negative`
266			`addcc %o3,%o5,%o3`
267			`b 9f`
268			`add %o2, (-1*2-1), %o2`
269
270
271			`.L3.15:`
272			`! remainder is negative`
273			`addcc %o3,%o5,%o3`
274			`! depth 4, accumulated bits -3`
275			`bl .L4.13`
276			`srl %o5,1,%o5`
277			`! remainder is positive`
278			`subcc %o3,%o5,%o3`
279			`b 9f`
280			`add %o2, (-3*2+1), %o2`
281
282			`.L4.13:`
283			`! remainder is negative`
284			`addcc %o3,%o5,%o3`
285			`b 9f`
286			`add %o2, (-3*2-1), %o2`
287
288
289
290			`.L2.15:`
291			`! remainder is negative`
292			`addcc %o3,%o5,%o3`
293			`! depth 3, accumulated bits -3`
294			`bl .L3.13`
295			`srl %o5,1,%o5`
296			`! remainder is positive`
297			`subcc %o3,%o5,%o3`
298			`! depth 4, accumulated bits -5`
299			`bl .L4.11`
300			`srl %o5,1,%o5`
301			`! remainder is positive`
302			`subcc %o3,%o5,%o3`
303			`b 9f`
304			`add %o2, (-5*2+1), %o2`
305
306			`.L4.11:`
307			`! remainder is negative`
308			`addcc %o3,%o5,%o3`
309			`b 9f`
310			`add %o2, (-5*2-1), %o2`
311
312
313			`.L3.13:`
314			`! remainder is negative`
315			`addcc %o3,%o5,%o3`
316			`! depth 4, accumulated bits -7`
317			`bl .L4.9`
318			`srl %o5,1,%o5`
319			`! remainder is positive`
320			`subcc %o3,%o5,%o3`
321			`b 9f`
322			`add %o2, (-7*2+1), %o2`
323
324			`.L4.9:`
325			`! remainder is negative`
326			`addcc %o3,%o5,%o3`
327			`b 9f`
328			`add %o2, (-7*2-1), %o2`
329
330
331
332
333			`9:`
334			`.Lend_regular_divide:`
335			`subcc %o4, 1, %o4`
336			`bge .Ldivloop`
337			`tst %o3`
338			`bl,a .Lgot_result`
339			`! non-restoring fixup here (one instruction only!)`
340			`sub %o2, 1, %o2`
341
342
343			`.Lgot_result:`
344
345			`retl`
346			`mov %o2, %o0`
347
348			`.size .udiv,.-.udiv;`