sparc/lib/udiv.S

2  * udiv.S:      This routine was taken from glibc-1.09 and is covered
26  *  TOPBITS	number of bits in the top decade of a number
29  *  Q		the partial quotient under development (initially 0)
34  *  V		the current comparand, initially divisor*2^(ITER*N-1)
37  *  Current estimate for non-large dividend is
39  *  A large dividend is one greater than 2^(31-TOPBITS) and takes a
41  *  one bit at a time.
52 	bne	1f
55 		! Divide by zero trap.  If it returns, return 0 (about as
66 	sethi	%hi(1 << (32 - 4 - 1)), %g1
72 	! Here the dividend is >= 2**(31-N) or so.  We must be careful here,
73 	! as our usual N-at-a-shot divide step will cause overflow and havoc.
79 		bgeu	3f
94 		! This means that %o3 has the high-order bit set.
111 	/* NB: these are commented out in the V8-Sparc manual as well */
116 	! do single-bit divide steps
120 	! and are only done if %o3 >= 0.  Because both %o3 and %o5 may have the high-
136 		bl	1f
138 		! %o3 >= 0
140 		b	2f
142 	1:	! %o3 < 0
151 		b,a	Lend_regular_divide
167 		! depth 1, accumulated bits 0
187 	b	9f
193 	b	9f
194 	 add	%o2, (7*2-1), %o2
204 	b	9f
210 	b	9f
211 	 add	%o2, (5*2-1), %o2
226 	b	9f
232 	b	9f
233 	 add	%o2, (3*2-1), %o2
243 	b	9f
249 	b	9f
250 	 add	%o2, (1*2-1), %o2
255 			! depth 2, accumulated bits -1
260 			! depth 3, accumulated bits -1
265 			! depth 4, accumulated bits -1
270 	b	9f
271 	 add	%o2, (-1*2+1), %o2
276 	b	9f
277 	 add	%o2, (-1*2-1), %o2
282 			! depth 4, accumulated bits -3
287 	b	9f
288 	 add	%o2, (-3*2+1), %o2
293 	b	9f
294 	 add	%o2, (-3*2-1), %o2
299 			! depth 3, accumulated bits -3
304 			! depth 4, accumulated bits -5
309 	b	9f
310 	 add	%o2, (-5*2+1), %o2
315 	b	9f
316 	 add	%o2, (-5*2-1), %o2
321 			! depth 4, accumulated bits -7
326 	b	9f
327 	 add	%o2, (-7*2+1), %o2
332 	b	9f
333 	 add	%o2, (-7*2-1), %o2
335 	9:
341 	bl,a	Lgot_result
342 	! non-restoring fixup here (one instruction only!)
352 	wr	%g0, 0x0, %y