1/*
  2 * rem.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
  7/* This file is generated from divrem.m4; DO NOT EDIT! */
  8/*
  9 * Division and remainder, from Appendix E of the Sparc Version 8
 10 * Architecture Manual, with fixes from Gordon Irlam.
 11 */
 12
 13/*
 14 * Input: dividend and divisor in %o0 and %o1 respectively.
 15 *
 16 * m4 parameters:
 17 *  .rem	name of function to generate
 18 *  rem		rem=div => %o0 / %o1; rem=rem => %o0 % %o1
 19 *  true		true=true => signed; true=false => unsigned
 20 *
 21 * Algorithm parameters:
 22 *  N		how many bits per iteration we try to get (4)
 23 *  WORDSIZE	total number of bits (32)
 24 *
 25 * Derived constants:
 26 *  TOPBITS	number of bits in the top decade of a number
 27 *
 28 * Important variables:
 29 *  Q		the partial quotient under development (initially 0)
 30 *  R		the remainder so far, initially the dividend
 31 *  ITER	number of main division loop iterations required;
 32 *		equal to ceil(log2(quotient) / N).  Note that this
 33 *		is the log base (2^N) of the quotient.
 34 *  V		the current comparand, initially divisor*2^(ITER*N-1)
 35 *
 36 * Cost:
 37 *  Current estimate for non-large dividend is
 38 *	ceil(log2(quotient) / N) * (10 + 7N/2) + C
 39 *  A large dividend is one greater than 2^(31-TOPBITS) and takes a
 40 *  different path, as the upper bits of the quotient must be developed
 41 *  one bit at a time.
 42 */
 43
 44
 45	.globl .rem
 46	.globl _Rem
 47.rem:
 48_Rem:	/* needed for export */
 49	! compute sign of result; if neither is negative, no problem
 50	orcc	%o1, %o0, %g0	! either negative?
 51	bge	2f			! no, go do the divide
 52	 mov	%o0, %g2	! compute sign in any case
 53
 54	tst	%o1
 55	bge	1f
 56	 tst	%o0
 57	! %o1 is definitely negative; %o0 might also be negative
 58	bge	2f			! if %o0 not negative...
 59	 sub	%g0, %o1, %o1	! in any case, make %o1 nonneg
 601:	! %o0 is negative, %o1 is nonnegative
 61	sub	%g0, %o0, %o0	! make %o0 nonnegative
 622:
 63
 64	! Ready to divide.  Compute size of quotient; scale comparand.
 65	orcc	%o1, %g0, %o5
 66	bne	1f
 67	 mov	%o0, %o3
 68
 69		! Divide by zero trap.  If it returns, return 0 (about as
 70		! wrong as possible, but that is what SunOS does...).
 71		ta	ST_DIV0
 72		retl
 73		 clr	%o0
 74
 751:
 76	cmp	%o3, %o5			! if %o1 exceeds %o0, done
 77	blu	Lgot_result		! (and algorithm fails otherwise)
 78	 clr	%o2
 79
 80	sethi	%hi(1 << (32 - 4 - 1)), %g1
 81
 82	cmp	%o3, %g1
 83	blu	Lnot_really_big
 84	 clr	%o4
 85
 86	! Here the dividend is >= 2**(31-N) or so.  We must be careful here,
 87	! as our usual N-at-a-shot divide step will cause overflow and havoc.
 88	! The number of bits in the result here is N*ITER+SC, where SC <= N.
 89	! Compute ITER in an unorthodox manner: know we need to shift V into
 90	! the top decade: so do not even bother to compare to R.
 91	1:
 92		cmp	%o5, %g1
 93		bgeu	3f
 94		 mov	1, %g7
 95
 96		sll	%o5, 4, %o5
 97
 98		b	1b
 99		 add	%o4, 1, %o4
100
101	! Now compute %g7.
102	2:
103		addcc	%o5, %o5, %o5
104
105		bcc	Lnot_too_big
106		 add	%g7, 1, %g7
107
108		! We get here if the %o1 overflowed while shifting.
109		! This means that %o3 has the high-order bit set.
110		! Restore %o5 and subtract from %o3.
111		sll	%g1, 4, %g1	! high order bit
112		srl	%o5, 1, %o5		! rest of %o5
113		add	%o5, %g1, %o5
114
115		b	Ldo_single_div
116		 sub	%g7, 1, %g7
117
118	Lnot_too_big:
119	3:
120		cmp	%o5, %o3
121		blu	2b
122		 nop
123
124		be	Ldo_single_div
125		 nop
126	/* NB: these are commented out in the V8-Sparc manual as well */
127	/* (I do not understand this) */
128	! %o5 > %o3: went too far: back up 1 step
129	!	srl	%o5, 1, %o5
130	!	dec	%g7
131	! do single-bit divide steps
132	!
133	! We have to be careful here.  We know that %o3 >= %o5, so we can do the
134	! first divide step without thinking.  BUT, the others are conditional,
135	! and are only done if %o3 >= 0.  Because both %o3 and %o5 may have the high-
136	! order bit set in the first step, just falling into the regular
137	! division loop will mess up the first time around.
138	! So we unroll slightly...
139	Ldo_single_div:
140		subcc	%g7, 1, %g7
141		bl	Lend_regular_divide
142		 nop
143
144		sub	%o3, %o5, %o3
145		mov	1, %o2
146
147		b	Lend_single_divloop
148		 nop
149	Lsingle_divloop:
150		sll	%o2, 1, %o2
151
152		bl	1f
153		 srl	%o5, 1, %o5
154		! %o3 >= 0
155		sub	%o3, %o5, %o3
156
157		b	2f
158		 add	%o2, 1, %o2
159	1:	! %o3 < 0
160		add	%o3, %o5, %o3
161		sub	%o2, 1, %o2
162	2:
163	Lend_single_divloop:
164		subcc	%g7, 1, %g7
165		bge	Lsingle_divloop
166		 tst	%o3
167
168		b,a	Lend_regular_divide
169
170Lnot_really_big:
1711:
172	sll	%o5, 4, %o5
173	cmp	%o5, %o3
174	bleu	1b
175	 addcc	%o4, 1, %o4
176	be	Lgot_result
177	 sub	%o4, 1, %o4
178
179	tst	%o3	! set up for initial iteration
180Ldivloop:
181	sll	%o2, 4, %o2
182		! depth 1, accumulated bits 0
183	bl	L.1.16
184	 srl	%o5,1,%o5
185	! remainder is positive
186	subcc	%o3,%o5,%o3
187			! depth 2, accumulated bits 1
188	bl	L.2.17
189	 srl	%o5,1,%o5
190	! remainder is positive
191	subcc	%o3,%o5,%o3
192			! depth 3, accumulated bits 3
193	bl	L.3.19
194	 srl	%o5,1,%o5
195	! remainder is positive
196	subcc	%o3,%o5,%o3
197			! depth 4, accumulated bits 7
198	bl	L.4.23
199	 srl	%o5,1,%o5
200	! remainder is positive
201	subcc	%o3,%o5,%o3
202
203	b	9f
204	 add	%o2, (7*2+1), %o2
205	
206L.4.23:
207	! remainder is negative
208	addcc	%o3,%o5,%o3
209	b	9f
210	 add	%o2, (7*2-1), %o2
211	
212L.3.19:
213	! remainder is negative
214	addcc	%o3,%o5,%o3
215			! depth 4, accumulated bits 5
216	bl	L.4.21
217	 srl	%o5,1,%o5
218	! remainder is positive
219	subcc	%o3,%o5,%o3
220	b	9f
221	 add	%o2, (5*2+1), %o2
222	
223L.4.21:
224	! remainder is negative
225	addcc	%o3,%o5,%o3
226	b	9f
227	 add	%o2, (5*2-1), %o2
228	
229L.2.17:
230	! remainder is negative
231	addcc	%o3,%o5,%o3
232			! depth 3, accumulated bits 1
233	bl	L.3.17
234	 srl	%o5,1,%o5
235	! remainder is positive
236	subcc	%o3,%o5,%o3
237			! depth 4, accumulated bits 3
238	bl	L.4.19
239	 srl	%o5,1,%o5
240	! remainder is positive
241	subcc	%o3,%o5,%o3
242	b	9f
243	 add	%o2, (3*2+1), %o2
244
245L.4.19:
246	! remainder is negative
247	addcc	%o3,%o5,%o3
248	b	9f
249	 add	%o2, (3*2-1), %o2
250
251L.3.17:
252	! remainder is negative
253	addcc	%o3,%o5,%o3
254			! depth 4, accumulated bits 1
255	bl	L.4.17
256	 srl	%o5,1,%o5
257	! remainder is positive
258	subcc	%o3,%o5,%o3
259	b	9f
260	 add	%o2, (1*2+1), %o2
261
262L.4.17:
263	! remainder is negative
264	addcc	%o3,%o5,%o3
265	b	9f
266	 add	%o2, (1*2-1), %o2
267
268L.1.16:
269	! remainder is negative
270	addcc	%o3,%o5,%o3
271			! depth 2, accumulated bits -1
272	bl	L.2.15
273	 srl	%o5,1,%o5
274	! remainder is positive
275	subcc	%o3,%o5,%o3
276			! depth 3, accumulated bits -1
277	bl	L.3.15
278	 srl	%o5,1,%o5
279	! remainder is positive
280	subcc	%o3,%o5,%o3
281			! depth 4, accumulated bits -1
282	bl	L.4.15
283	 srl	%o5,1,%o5
284	! remainder is positive
285	subcc	%o3,%o5,%o3
286	b	9f
287	 add	%o2, (-1*2+1), %o2
288
289L.4.15:
290	! remainder is negative
291	addcc	%o3,%o5,%o3
292	b	9f
293	 add	%o2, (-1*2-1), %o2
294
295L.3.15:
296	! remainder is negative
297	addcc	%o3,%o5,%o3
298			! depth 4, accumulated bits -3
299	bl	L.4.13
300	 srl	%o5,1,%o5
301	! remainder is positive
302	subcc	%o3,%o5,%o3
303	b	9f
304	 add	%o2, (-3*2+1), %o2
305
306L.4.13:
307	! remainder is negative
308	addcc	%o3,%o5,%o3
309	b	9f
310	 add	%o2, (-3*2-1), %o2
311
312L.2.15:
313	! remainder is negative
314	addcc	%o3,%o5,%o3
315			! depth 3, accumulated bits -3
316	bl	L.3.13
317	 srl	%o5,1,%o5
318	! remainder is positive
319	subcc	%o3,%o5,%o3
320			! depth 4, accumulated bits -5
321	bl	L.4.11
322	 srl	%o5,1,%o5
323	! remainder is positive
324	subcc	%o3,%o5,%o3
325	b	9f
326	 add	%o2, (-5*2+1), %o2
327
328L.4.11:
329	! remainder is negative
330	addcc	%o3,%o5,%o3
331	b	9f
332	 add	%o2, (-5*2-1), %o2
333
334
335L.3.13:
336	! remainder is negative
337	addcc	%o3,%o5,%o3
338			! depth 4, accumulated bits -7
339	bl	L.4.9
340	 srl	%o5,1,%o5
341	! remainder is positive
342	subcc	%o3,%o5,%o3
343	b	9f
344	 add	%o2, (-7*2+1), %o2
345
346L.4.9:
347	! remainder is negative
348	addcc	%o3,%o5,%o3
349	b	9f
350	 add	%o2, (-7*2-1), %o2
351
352	9:
353Lend_regular_divide:
354	subcc	%o4, 1, %o4
355	bge	Ldivloop
356	 tst	%o3
357
358	bl,a	Lgot_result
359	! non-restoring fixup here (one instruction only!)
360	add	%o3, %o1, %o3
361
362Lgot_result:
363	! check to see if answer should be < 0
364	tst	%g2
365	bl,a	1f
366	 sub %g0, %o3, %o3
3671:
368	retl
369	 mov %o3, %o0
370
371	.globl	.rem_patch
372.rem_patch:
373	sra	%o0, 0x1f, %o4
374	wr	%o4, 0x0, %y
375	nop
376	nop
377	nop
378	sdivcc	%o0, %o1, %o2
379	bvs,a	1f
380	 xnor	%o2, %g0, %o2
3811:	smul	%o2, %o1, %o2
382	retl
383	 sub	%o0, %o2, %o0
384	nop