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1.1 maekawa 1: dnl AMD K6-2 mpn_lshift -- mpn left shift.
2: dnl
3: dnl K6-2: 1.75 cycles/limb
4:
5:
6: dnl Copyright (C) 1999, 2000 Free Software Foundation, Inc.
7: dnl
8: dnl This file is part of the GNU MP Library.
9: dnl
10: dnl The GNU MP Library is free software; you can redistribute it and/or
11: dnl modify it under the terms of the GNU Lesser General Public License as
12: dnl published by the Free Software Foundation; either version 2.1 of the
13: dnl License, or (at your option) any later version.
14: dnl
15: dnl The GNU MP Library is distributed in the hope that it will be useful,
16: dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
17: dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18: dnl Lesser General Public License for more details.
19: dnl
20: dnl You should have received a copy of the GNU Lesser General Public
21: dnl License along with the GNU MP Library; see the file COPYING.LIB. If
22: dnl not, write to the Free Software Foundation, Inc., 59 Temple Place -
23: dnl Suite 330, Boston, MA 02111-1307, USA.
24:
25:
26: include(`../config.m4')
27:
28:
29: C mp_limb_t mpn_lshift (mp_ptr dst, mp_srcptr src, mp_size_t size,
30: C unsigned shift);
31: C
32:
33: defframe(PARAM_SHIFT,16)
34: defframe(PARAM_SIZE, 12)
35: defframe(PARAM_SRC, 8)
36: defframe(PARAM_DST, 4)
37: deflit(`FRAME',0)
38:
39: dnl used after src has been fetched
40: define(VAR_RETVAL,`PARAM_SRC')
41:
42: dnl minimum 9, because unrolled loop can't handle less
43: deflit(UNROLL_THRESHOLD, 9)
44:
45: .text
46: ALIGN(32)
47:
48: PROLOGUE(mpn_lshift)
49: deflit(`FRAME',0)
50:
51: C The 1 limb case can be done without the push %ebx, but it's then
52: C still the same speed. The push is left as a free helping hand for
53: C the two_or_more code.
54:
55: movl PARAM_SIZE, %eax
56: pushl %ebx FRAME_pushl()
57:
58: movl PARAM_SRC, %ebx
59: decl %eax
60:
61: movl PARAM_SHIFT, %ecx
62: jnz L(two_or_more)
63:
64: movl (%ebx), %edx C src limb
65: movl PARAM_DST, %ebx
66:
67: shldl( %cl, %edx, %eax) C return value
68:
69: shll %cl, %edx
70:
71: movl %edx, (%ebx) C dst limb
72: popl %ebx
73:
74: ret
75:
76:
77: C -----------------------------------------------------------------------------
78: ALIGN(16) C avoid offset 0x1f
79: L(two_or_more):
80: C eax size-1
81: C ebx src
82: C ecx shift
83: C edx
84:
85: movl (%ebx,%eax,4), %edx C src high limb
86: negl %ecx
87:
88: movd PARAM_SHIFT, %mm6
89: addl $32, %ecx C 32-shift
90:
91: shrl %cl, %edx
92: cmpl $UNROLL_THRESHOLD-1, %eax
93:
94: movl %edx, VAR_RETVAL
95: jae L(unroll)
96:
97:
98: movd %ecx, %mm7
99: movl %eax, %ecx
100:
101: movl PARAM_DST, %eax
102:
103: L(simple):
104: C eax dst
105: C ebx src
106: C ecx counter, size-1 to 1
107: C edx retval
108: C
109: C mm0 scratch
110: C mm6 shift
111: C mm7 32-shift
112:
113: movq -4(%ebx,%ecx,4), %mm0
114:
115: psrlq %mm7, %mm0
116:
117: Zdisp( movd, %mm0, 0,(%eax,%ecx,4))
118: loop L(simple)
119:
120:
121: movd (%ebx), %mm0
122: popl %ebx
123:
124: psllq %mm6, %mm0
125:
126: movd %mm0, (%eax)
127: movl %edx, %eax
128:
129: femms
130: ret
131:
132:
133: C -----------------------------------------------------------------------------
134: ALIGN(16)
135: L(unroll):
136: C eax size-1
137: C ebx src
138: C ecx 32-shift
139: C edx retval (but instead VAR_RETVAL is used)
140: C
141: C mm6 shift
142:
143: addl $32, %ecx
144: movl PARAM_DST, %edx
145:
146: movd %ecx, %mm7
147: subl $7, %eax C size-8
148:
149: leal (%edx,%eax,4), %ecx C alignment of dst
150:
151: movq 32-8(%ebx,%eax,4), %mm2 C src high qword
152: testb $4, %cl
153:
154: jz L(dst_aligned)
155: psllq %mm6, %mm2
156:
157: psrlq $32, %mm2
158: decl %eax
159:
160: movd %mm2, 32(%edx,%eax,4) C dst high limb
161: movq 32-8(%ebx,%eax,4), %mm2 C new src high qword
162: L(dst_aligned):
163:
164: movq 32-16(%ebx,%eax,4), %mm0 C src second highest qword
165:
166:
167: C This loop is the important bit, the rest is just support for it.
168: C Four src limbs are held at the start, and four more will be read.
169: C Four dst limbs will be written. This schedule seems necessary for
170: C full speed.
171: C
172: C The use of size-8 lets the loop stop when %eax goes negative and
173: C leaves -4 to -1 which can be tested with test $1 and $2.
174:
175: L(top):
176: C eax counter, size-8 step by -4 until <0
177: C ebx src
178: C ecx
179: C edx dst
180: C
181: C mm0 src next qword
182: C mm1 scratch
183: C mm2 src prev qword
184: C mm6 shift
185: C mm7 64-shift
186:
187: psllq %mm6, %mm2
188: subl $4, %eax
189:
190: movq %mm0, %mm1
191: psrlq %mm7, %mm0
192:
193: por %mm0, %mm2
194: movq 24(%ebx,%eax,4), %mm0
195:
196: psllq %mm6, %mm1
197: movq %mm2, 40(%edx,%eax,4)
198:
199: movq %mm0, %mm2
200: psrlq %mm7, %mm0
201:
202: por %mm0, %mm1
203: movq 16(%ebx,%eax,4), %mm0
204:
205: movq %mm1, 32(%edx,%eax,4)
206: jnc L(top)
207:
208:
209: C Now have four limbs in mm2 (prev) and mm0 (next), plus eax mod 4.
210: C
211: C 8(%ebx) is the next source, and 24(%edx) is the next destination.
212: C %eax is between -4 and -1, representing respectively 0 to 3 extra
213: C limbs that must be read.
214:
215:
216: testl $2, %eax C testl to avoid bad cache line crossing
217: jz L(finish_nottwo)
218:
219: C Two more limbs: lshift mm2, OR it with rshifted mm0, mm0 becomes
220: C new mm2 and a new mm0 is loaded.
221:
222: psllq %mm6, %mm2
223: movq %mm0, %mm1
224:
225: psrlq %mm7, %mm0
226: subl $2, %eax
227:
228: por %mm0, %mm2
229: movq 16(%ebx,%eax,4), %mm0
230:
231: movq %mm2, 32(%edx,%eax,4)
232: movq %mm1, %mm2
233: L(finish_nottwo):
234:
235:
236: C lshift mm2, OR with rshifted mm0, mm1 becomes lshifted mm0
237:
238: testb $1, %al
239: psllq %mm6, %mm2
240:
241: movq %mm0, %mm1
242: psrlq %mm7, %mm0
243:
244: por %mm0, %mm2
245: psllq %mm6, %mm1
246:
247: movq %mm2, 24(%edx,%eax,4)
248: jz L(finish_even)
249:
250:
251: C Size is odd, so mm1 and one extra limb to process.
252:
253: movd (%ebx), %mm0 C src[0]
254: popl %ebx
255: deflit(`FRAME',0)
256:
257: movq %mm0, %mm2
258: psllq $32, %mm0
259:
260: psrlq %mm7, %mm0
261:
262: psllq %mm6, %mm2
263: por %mm0, %mm1
264:
265: movq %mm1, 4(%edx) C dst[1,2]
266: movd %mm2, (%edx) C dst[0]
267:
268: movl VAR_RETVAL, %eax
269:
270: femms
271: ret
272:
273:
274: nop C avoid bad cache line crossing
275: L(finish_even):
276: deflit(`FRAME',4)
277: C Size is even, so only mm1 left to process.
278:
279: movq %mm1, (%edx) C dst[0,1]
280: movl VAR_RETVAL, %eax
281:
282: popl %ebx
283: femms
284: ret
285:
286: EPILOGUE()