3 // Support for 16-bit unsigned division/modulus.
5 // Copyright (C) 2003-2014 Free Software Foundation, Inc.
6 // Contributed by Picochip Ltd.
7 // Maintained by Daniel Towner (daniel.towner@picochip.com)
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
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.
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.
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/>.
32 _picoMark_FUNCTION_BEGIN=
34 // picoChip Function Prologue : &__udivmodhi4 = 6 bytes
36 // 16-bit unsigned division. The divstep function is only capable of
37 // handling 15-bit division (plus a sign to give 16-bits). It is not
38 // capable of handling unsigned division directly. Instead, take
39 // advantage of the special property that
40 // ((divisor / 2) / dividend) * 2 will be almost good enough. The
41 // error in the result is only 0 or 1, and this can be easily
42 // tested and corrected. A full description of the algorithm can
43 // be found in `Hacker's Delight', by Henry Warren, page 146.
52 // Note that the lr, and original inputs are speculatively saved. They
53 // will only be restored if the 15-bit division function is called.
55 sub.0 r1,0,r15 \ stl r[0:1],(fp)-1
57 =-> sub.0 r0,r1,r2 \ stw lr,(fp)-3
59 // The divisor is >= 2^15.
62 // The dividend < divisor. The quotient is thus 0, and the
63 // remainder is the dividend.
64 copy.0 r0,r1 \ jr (lr)
68 // The dividend >= divisor. The quotient is thus 1, and the
69 // remainder can be computed directly by subtraction (i.e., the
70 // result of the comparison already performed to branch here).
71 jr (lr) \ copy.0 r2,r1
75 // The divisor is < 2^15.
77 // Divide the original dividend by 2, and call the 15-bit division.
78 // Note that the original dividend is stored in r5, which is
79 // known to be unused by the called function, so that
80 // a memory stall isn't introduced immediately after the
81 // function returns, to reload this value from memory.
83 jl (&__divmod15) \ copy.0 r0,r5 // fn_call &__divmod15
86 // Compute the new quotient and remainder by multiplying them by 2.
87 // The remainder will be 1 out, if the original dividend was odd.
88 and.0 r5,1,r5 \ ldl (fp)-1,r[2:3]
89 add.0 [lsl r1,1],r5,r1 \ lsl.1 r0,1,r0
91 // The error in the quotient is 0 or 1. The error can be determined
92 // by comparing the remainder to the original divisor. If the
93 // remainder is bigger, then an error of 1 has been introduced.
94 sub.0 r1,r3,r15 \ ldw (fp)-3,lr
97 add.0 r0,1,r0 \ sub.1 r1,r3,r1
101 _picoMark_FUNCTION_END=
102 // picoChip Function Epilogue : udivmodhi4
105 //============================================================================
106 // All DWARF information between this marker, and the END OF DWARF
107 // marker should be included in the source file. Search for
108 // FUNCTION_STACK_SIZE_GOES_HERE and FUNCTION NAME GOES HERE, and
109 // provide the relevant information. Add markers called
110 // _picoMark_FUNCTION_BEGIN and _picoMark_FUNCTION_END around the
111 // function in question.
112 //============================================================================
114 //============================================================================
115 // Frame information.
116 //============================================================================
118 .section .debug_frame
119 _picoMark_DebugFrame=
121 // Common CIE header.
122 .unalignedInitLong _picoMark_CieEnd-_picoMark_CieBegin
124 .unalignedInitLong 0xffffffff
125 .initByte 0x1 // CIE Version
126 .ascii 16#0# // CIE Augmentation
127 .uleb128 0x1 // CIE Code Alignment Factor
128 .sleb128 2 // CIE Data Alignment Factor
129 .initByte 0xc // CIE RA Column
130 .initByte 0xc // DW_CFA_def_cfa
137 _picoMark_LSFDE0I900821033007563=
138 .unalignedInitLong _picoMark_FdeEnd-_picoMark_FdeBegin
140 .unalignedInitLong _picoMark_DebugFrame // FDE CIE offset
141 .unalignedInitWord _picoMark_FUNCTION_BEGIN // FDE initial location
142 .unalignedInitWord _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN
143 .initByte 0xe // DW_CFA_def_cfa_offset
144 .uleb128 0x6 // <-- FUNCTION_STACK_SIZE_GOES_HERE
145 .initByte 0x4 // DW_CFA_advance_loc4
146 .unalignedInitLong _picoMark_FUNCTION_END-_picoMark_FUNCTION_BEGIN
147 .initByte 0xe // DW_CFA_def_cfa_offset
152 //============================================================================
153 // Abbrevation information.
154 //============================================================================
156 .section .debug_abbrev
157 _picoMark_ABBREVIATIONS=
159 .section .debug_abbrev
160 .uleb128 0x1 // (abbrev code)
161 .uleb128 0x11 // (TAG: DW_TAG_compile_unit)
162 .initByte 0x1 // DW_children_yes
163 .uleb128 0x10 // (DW_AT_stmt_list)
164 .uleb128 0x6 // (DW_FORM_data4)
165 .uleb128 0x12 // (DW_AT_high_pc)
166 .uleb128 0x1 // (DW_FORM_addr)
167 .uleb128 0x11 // (DW_AT_low_pc)
168 .uleb128 0x1 // (DW_FORM_addr)
169 .uleb128 0x25 // (DW_AT_producer)
170 .uleb128 0x8 // (DW_FORM_string)
171 .uleb128 0x13 // (DW_AT_language)
172 .uleb128 0x5 // (DW_FORM_data2)
173 .uleb128 0x3 // (DW_AT_name)
174 .uleb128 0x8 // (DW_FORM_string)
178 .uleb128 0x2 ;# (abbrev code)
179 .uleb128 0x2e ;# (TAG: DW_TAG_subprogram)
180 .initByte 0x0 ;# DW_children_no
181 .uleb128 0x3 ;# (DW_AT_name)
182 .uleb128 0x8 ;# (DW_FORM_string)
183 .uleb128 0x11 ;# (DW_AT_low_pc)
184 .uleb128 0x1 ;# (DW_FORM_addr)
185 .uleb128 0x12 ;# (DW_AT_high_pc)
186 .uleb128 0x1 ;# (DW_FORM_addr)
192 //============================================================================
193 // Line information. DwarfLib requires this to be present, but it can
195 //============================================================================
200 //============================================================================
202 //============================================================================
206 .unalignedInitLong _picoMark_DEBUG_INFO_END-_picoMark_DEBUG_INFO_BEGIN
207 _picoMark_DEBUG_INFO_BEGIN=
208 .unalignedInitWord 0x2
209 .unalignedInitLong _picoMark_ABBREVIATIONS
212 // Compile unit information.
213 .uleb128 0x1 // (DIE 0xb) DW_TAG_compile_unit)
214 .unalignedInitLong _picoMark_LINES
215 .unalignedInitWord _picoMark_FUNCTION_END
216 .unalignedInitWord _picoMark_FUNCTION_BEGIN
217 // Producer is `picoChip'
218 .ascii 16#70# 16#69# 16#63# 16#6f# 16#43# 16#68# 16#69# 16#70# 16#00#
219 .unalignedInitWord 0xcafe // ASM language
220 .ascii 16#0# // Name. DwarfLib expects this to be present.
222 .uleb128 0x2 ;# (DIE DW_TAG_subprogram)
224 // FUNCTION NAME GOES HERE. Use `echo name | od -t x1' to get the hex. Each hex
225 // digit is specified using the format 16#XX#
226 .ascii 16#5f# 16#75# 16#64# 16#69# 16#76# 16#6d# 16#6f# 16#64# 16#68# 16#69# 16#34# 16#0# // Function name `_udivmodhi4'
227 .unalignedInitWord _picoMark_FUNCTION_BEGIN // DW_AT_low_pc
228 .unalignedInitWord _picoMark_FUNCTION_END // DW_AT_high_pc
230 .initByte 0x0 // end of compile unit children.
232 _picoMark_DEBUG_INFO_END=
234 //============================================================================
236 //============================================================================
238 // End of picoChip ASM file