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comparison gcc/config/picochip/libgccExtras/divmodhi4.asm @ 0:a06113de4d67

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author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
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1 // picoChip ASM file
2 //
3 // Support for 16-bit signed division/modulus.
4 //
5 // Copyright (C) 2003, 2004, 2005, 2008, 2009 Free Software Foundation, Inc.
6 // Contributed by picoChip Designs Ltd.
7 // Maintained by Daniel Towner (daniel.towner@picochip.com)
8 //
9 // This file is free software; you can redistribute it and/or modify it
10 // under the terms of the GNU General Public License as published by the
11 // Free Software Foundation; either version 3, or (at your option) any
12 // later version.
13 //
14 // This file is distributed in the hope that it will be useful, but
15 // WITHOUT ANY WARRANTY; without even the implied warranty of
16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 // General Public License for more details.
18 //
19 // Under Section 7 of GPL version 3, you are granted additional
20 // permissions described in the GCC Runtime Library Exception, version
21 // 3.1, as published by the Free Software Foundation.
22 //
23 // You should have received a copy of the GNU General Public License and
24 // a copy of the GCC Runtime Library Exception along with this program;
25 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
26 // <http://www.gnu.org/licenses/>.
27
28 .section .text
29
30 .align 8
31 .global __divmodhi4
32 __divmodhi4:
33 _picoMark_FUNCTION_BEGIN=
34
35 // picoChip Function Prologue : &__divmodhi4 = 4 bytes
36
37 // 16-bit signed division. Most of the special cases are dealt
38 // with by the 15-bit signed division library (e.g., division by
39 // zero, division by 1, and so on). This wrapper simply inverts
40 // any negative inputs, calls the 15-bit library, and flips any
41 // results as necessary. The
42 // only special cases to be handled here are where either the
43 // divisor or the dividend are the maximum negative values.
44
45 // Encode r5 with a bit pattern which indicates whether the
46 // outputs of the division must be negated. The MSB will be set
47 // to the sign of the dividend (which controls the remainder's
48 // sign), while the LSB will store the XOR of the two signs,
49 // which indicates the quotient's sign. R5 is not modified by the
50 // 15-bit divmod routine.
51 sub.0 r1,16#8000#,r15 \ asr.1 r0,15,r4
52 beq divisorIsLargestNegative \ lsr.0 r1,15,r3
53 =-> sub.0 r0,16#8000#,r15 \ xor.1 r3,r4,r5
54
55 // Handle least negative dividend with a special case. Note that the
56 // absolute value of the divisor is also computed here.
57 add.0 [asr r1,15],r1,r3 \ beq dividendIsLargestNegative
58 =-> xor.0 [asr r1,15],r3,r1 \ stw lr,(fp)-1
59
60 // Compute the absolute value of the dividend, and call the main
61 // divide routine.
62 add.0 r4,r0,r2 \ jl (&__divmod15) // fn_call &__divmod15
63 =-> xor.0 r4,r2,r0
64
65 handleNegatedResults:
66 // Speculatively store the negation of the results.
67 sub.0 0,r0,r2 \ sub.1 0,r1,r3
68
69 // Does the quotient need negating? The LSB indicates this.
70 and.0 r5,1,r15 \ ldw (fp)-1,lr
71 copyne r2,r0
72
73 asr.0 r5,15,r15 \ jr (lr)
74 =-> copyne r3,r1
75
76 dividendIsLargestNegative:
77
78 // Divide the constant -32768. Use the Hacker's Delight
79 // algorithm (i.e., ((dividend / 2) / divisor) * 2) gives
80 // approximate answer). This code is a special case, so no
81 // great effort is made to make it fast, only to make it
82 // small.
83
84 lsr.0 r0,1,r0 \ jl (&__divmod15) // fn_call &__divmod15
85 =-> stw r1,(fp)-2
86
87 // Load the original divisor, and compute the new quotient and
88 // remainder.
89 lsl.0 r0,1,r0 \ ldw (fp)-2,r3
90 lsl.0 r1,1,r1 // Fill stall slot
91
92 // The error in the quotient is 0 or 1. The error can be determined
93 // by comparing the remainder to the original divisor. If the
94 // remainder is bigger, then an error of 1 has been introduced,
95 // which must be fixed.
96 sub.0 r1,r3,r15
97 blo noCompensationForError
98 =-> nop
99 add.0 r0,1,r0 \ sub.1 r1,r3,r1
100 noCompensationForError:
101 bra handleNegatedResults
102 =-> nop
103
104 divisorIsLargestNegative:
105 // The flags indicate whether the dividend is also the maximum negative
106 copy.0 r0,r1 \ copy.1 0,r0
107 copyeq r0,r1 \ jr (lr)
108 =-> copyeq 1,r0
109
110 _picoMark_FUNCTION_END=
111 // picoChip Function Epilogue : __divmodhi4
112
113
114 //============================================================================
115 // All DWARF information between this marker, and the END OF DWARF
116 // marker should be included in the source file. Search for
117 // FUNCTION_STACK_SIZE_GOES_HERE and FUNCTION NAME GOES HERE, and
118 // provide the relevent information. Add markers called
119 // _picoMark_FUNCTION_BEGIN and _picoMark_FUNCTION_END around the
120 // function in question.
121 //============================================================================
122
123 //============================================================================
124 // Frame information.
125 //============================================================================
126
127 .section .debug_frame
128 _picoMark_DebugFrame=
129
130 // Common CIE header.
131 .unalignedInitLong _picoMark_CieEnd-_picoMark_CieBegin
132 _picoMark_CieBegin=
133 .unalignedInitLong 0xffffffff
134 .initByte 0x1 // CIE Version
135 .ascii 16#0# // CIE Augmentation
136 .uleb128 0x1 // CIE Code Alignment Factor
137 .sleb128 2 // CIE Data Alignment Factor
138 .initByte 0xc // CIE RA Column
139 .initByte 0xc // DW_CFA_def_cfa
140 .uleb128 0xd
141 .uleb128 0x0
142 .align 2
143 _picoMark_CieEnd=
144
145 // FDE
146 _picoMark_LSFDE0I900821033007563=
147 .unalignedInitLong _picoMark_FdeEnd-_picoMark_FdeBegin
148 _picoMark_FdeBegin=
149 .unalignedInitLong _picoMark_DebugFrame // FDE CIE offset
150 .unalignedInitWord _picoMark_FUNCTION_BEGIN // FDE initial location
151 .unalignedInitWord _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN
152 .initByte 0xe // DW_CFA_def_cfa_offset
153 .uleb128 0x4 // <-- FUNCTION_STACK_SIZE_GOES_HERE
154 .initByte 0x4 // DW_CFA_advance_loc4
155 .unalignedInitLong _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN
156 .initByte 0xe // DW_CFA_def_cfa_offset
157 .uleb128 0x0
158 .align 2
159 _picoMark_FdeEnd=
160
161 //============================================================================
162 // Abbrevation information.
163 //============================================================================
164
165 .section .debug_abbrev
166 _picoMark_ABBREVIATIONS=
167
168 .section .debug_abbrev
169 .uleb128 0x1 // (abbrev code)
170 .uleb128 0x11 // (TAG: DW_TAG_compile_unit)
171 .initByte 0x1 // DW_children_yes
172 .uleb128 0x10 // (DW_AT_stmt_list)
173 .uleb128 0x6 // (DW_FORM_data4)
174 .uleb128 0x12 // (DW_AT_high_pc)
175 .uleb128 0x1 // (DW_FORM_addr)
176 .uleb128 0x11 // (DW_AT_low_pc)
177 .uleb128 0x1 // (DW_FORM_addr)
178 .uleb128 0x25 // (DW_AT_producer)
179 .uleb128 0x8 // (DW_FORM_string)
180 .uleb128 0x13 // (DW_AT_language)
181 .uleb128 0x5 // (DW_FORM_data2)
182 .uleb128 0x3 // (DW_AT_name)
183 .uleb128 0x8 // (DW_FORM_string)
184 .initByte 0x0
185 .initByte 0x0
186
187 .uleb128 0x2 ;# (abbrev code)
188 .uleb128 0x2e ;# (TAG: DW_TAG_subprogram)
189 .initByte 0x0 ;# DW_children_no
190 .uleb128 0x3 ;# (DW_AT_name)
191 .uleb128 0x8 ;# (DW_FORM_string)
192 .uleb128 0x11 ;# (DW_AT_low_pc)
193 .uleb128 0x1 ;# (DW_FORM_addr)
194 .uleb128 0x12 ;# (DW_AT_high_pc)
195 .uleb128 0x1 ;# (DW_FORM_addr)
196 .initByte 0x0
197 .initByte 0x0
198
199 .initByte 0x0
200
201 //============================================================================
202 // Line information. DwarfLib requires this to be present, but it can
203 // be empty.
204 //============================================================================
205
206 .section .debug_line
207 _picoMark_LINES=
208
209 //============================================================================
210 // Debug Information
211 //============================================================================
212 .section .debug_info
213
214 //Fixed header.
215 .unalignedInitLong _picoMark_DEBUG_INFO_END-_picoMark_DEBUG_INFO_BEGIN
216 _picoMark_DEBUG_INFO_BEGIN=
217 .unalignedInitWord 0x2
218 .unalignedInitLong _picoMark_ABBREVIATIONS
219 .initByte 0x2
220
221 // Compile unit information.
222 .uleb128 0x1 // (DIE 0xb) DW_TAG_compile_unit)
223 .unalignedInitLong _picoMark_LINES
224 .unalignedInitWord _picoMark_FUNCTION_END
225 .unalignedInitWord _picoMark_FUNCTION_BEGIN
226 // Producer is `picoChip'
227 .ascii 16#70# 16#69# 16#63# 16#6f# 16#43# 16#68# 16#69# 16#70# 16#00#
228 .unalignedInitWord 0xcafe // ASM language
229 .ascii 16#0# // Name. DwarfLib expects this to be present.
230
231 .uleb128 0x2 ;# (DIE DW_TAG_subprogram)
232
233 // FUNCTION NAME GOES HERE. Use `echo name | od -t x1' to get the hex. Each hex
234 // digit is specified using the format 16#XX#
235 .ascii 16#5f# 16#64# 16#69# 16#76# 16#6d# 16#6f# 16#64# 16#68# 16#69# 16#34# 16#0# // Function name `_divmodhi4'
236 .unalignedInitWord _picoMark_FUNCTION_BEGIN // DW_AT_low_pc
237 .unalignedInitWord _picoMark_FUNCTION_END // DW_AT_high_pc
238
239 .initByte 0x0 // end of compile unit children.
240
241 _picoMark_DEBUG_INFO_END=
242
243 //============================================================================
244 // END OF DWARF
245 //============================================================================
246 .section .endFile