hppa/spmath/impys.S

62 op1:	.equ		5		/* multiplicand */
74 	stws,ma		op1,4(%sp)		; save registers on stack
84 	ldws		0(%arg0),op1		; get multiplicand
87 	xor		op2,op1,sign		; sign(0) = sign of product
88 mpy1:	comb,<		op1,gr0,mpya		; br. if multiplicand < 0
90 	addib,=		0,op1,fini0		; op1 = 0, product = 0
116 ;  ----	bits = 0001 ---- add op1, then shift 4 bits
118 	addb,tr		op1,pu,sh4n+4		; add op1 to product, to shift
121 ;  ----	bits = 0010 ---- add op1, add op1, then shift 4 bits
123 	addb,tr		op1,pu,sh4n		; add 2*op1, to shift
124 	addb,uv		op1,pu,sh4c		;   product right 4 bits
126 ;  ---- bits = 0011 ---- add op1, add 2*op1, shift 4 bits
128 	addb,tr		op1,pu,sh4n-4		; add op1 & 2*op1, shift
129 	sh1add,nsv	op1,pu,pu		;   product right 4 bits
131 ;  ----	bits = 0100 ---- shift 2, add op1, shift 2
136 ;  ----	bits = 0101 ---- add op1, shift 2, add op1, and shift 2 again
138 	addb,tr		op1,pu,sh2us		; add op1 to product
141 ;  ----	bits = 0110 ---- add op1, add op1, shift 2, add op1, and shift 2 again
143 	addb,tr		op1,pu,sh2c		; add 2*op1, to shift 2 bits
144 	addb,nuv	op1,pu,sh2us		; br. if not overflow
146 ;  ----	bits = 0111 ---- subtract op1, shift 3, add op1, and shift 1
149 	sub		pu,op1,pu		; subtract op1, br. to sh3s
152 ;  ----	bits = 1000 ---- shift 3, add op1, shift 1
157 ;  ----	bits = 1001 ---- add op1, shift 3, add op1, shift 1
159 	addb,tr		op1,pu,sh3us		; add op1, to shift 3, add op1,
162 ;  ----	bits = 1010 ---- add op1, add op1, shift 3, add op1, shift 1
164 	addb,tr		op1,pu,sh3c		; add 2*op1, to shift 3 bits
165 	addb,nuv	op1,pu,sh3us		;   br. if no overflow
167 ;  ----	bits = 1011 ---- add -op1, shift 2, add -op1, shift 2, inc. next index
169 	addib,tr	1,brindex,sh2s		; add 1 to index, subtract op1,
170 	sub		pu,op1,pu		;   shift 2 with minus sign
172 ;  ----	bits = 1100 ---- shift 2, subtract op1, shift 2, increment next index
177 ;  ----	bits = 1101 ---- add op1, shift 2, add -op1, shift 2
179 	addb,tr		op1,pu,sh2ns		; add op1, to shift 2
182 ;  ----	bits = 1110 ---- shift 1 signed, add -op1, shift 3 signed
187 ;  ----	bits = 1111 ---- add -op1, shift 4 signed
189 	addib,tr	1,brindex,sh4s		; add 1 to index, subtract op1,
190 	sub		pu,op1,pu		;   to shift 4 signed
212 	add,>=		op1,gr0,gr0		; if op1 < 0, invert sign,
215 ;	special case for multiplier = -2**31, op1 = signed multiplicand
216 ;		or multiplicand = -2**31, op1 = signed multiplier
218 	shd		op1,0,1,pl		; shift op1 left 31 bits
219 mmax:	extrs		op1,30,31,pu
223 mpya:	add,=		op1,op1,gr0		; op1 = -2**31, special case
225 	sub		0,op1,op1		; op1 = |multiplicand|
228 	movb,tr		op2,op1,mmax		; use op2 as multiplicand
229 	shd		op1,0,1,pl		; shift it left 31 bits
233 	addb,tr		op1,pu,sh1		; add op1, to shift 1 bit
237 	addb,tr		op1,pu,sh1		; add op1, to shift 1 bit
241 	addb,tr		op1,pu,sh1		; add op1, to shift 1 bit
246 	addb,tr		op1,pu,sh1		; add op1, to shift 1 bit
259 	sub		pu,op1,pu		; subtract op1
266 	sub		pu,op1,pu		; subtract op1 from product
273 	sub		pu,op1,pu		; subtract op1 from product
278 fini0:	movib,tr,n	0,pl,fini		; product = 0 as op1 = 0
281 	addb,tr		op1,pu,sh2a		; add op1
286 	addb,tr		op1,pu,sh2a		; add op1 to product
290 	addb,tr		op1,pu,sh2a		; add op1 to product
310 	ldws,mb		-4(%sp),op1		; restore registers