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1 | @c Copyright 2012, 2013 Free Software Foundation, Inc. |
2 | @c This is part of the GAS manual. | |
3 | @c For copying conditions, see the file as.texinfo. | |
4 | @c man end | |
5 | @ifset GENERIC | |
6 | @page | |
7 | @node NiosII-Dependent | |
8 | @chapter Nios II Dependent Features | |
9 | @end ifset | |
10 | @ifclear GENERIC | |
11 | @node Machine Dependencies | |
12 | @chapter Nios II Dependent Features | |
13 | @end ifclear | |
14 | ||
15 | @cindex Altera Nios II support | |
16 | @cindex Nios support | |
17 | @cindex Nios II support | |
18 | @menu | |
19 | * Nios II Options:: Options | |
20 | * Nios II Syntax:: Syntax | |
21 | * Nios II Relocations:: Relocations | |
22 | * Nios II Directives:: Nios II Machine Directives | |
23 | * Nios II Opcodes:: Opcodes | |
24 | @end menu | |
25 | ||
26 | @node Nios II Options | |
27 | @section Options | |
28 | @cindex Nios II options | |
29 | @cindex options for Nios II | |
30 | ||
31 | @c man begin OPTIONS | |
32 | @table @gcctabopt | |
33 | ||
34 | @cindex @code{relax-section} command line option, Nios II | |
35 | @item -relax-section | |
36 | Replace identified out-of-range branches with PC-relative @code{jmp} | |
37 | sequences when possible. The generated code sequences are suitable | |
38 | for use in position-independent code, but there is a practical limit | |
39 | on the extended branch range because of the length of the sequences. | |
40 | This option is the default. | |
41 | ||
42 | @cindex @code{relax-all} command line option, Nios II | |
43 | @item -relax-all | |
44 | Replace branch instructions not determinable to be in range | |
45 | and all call instructions with @code{jmp} and @code{callr} sequences | |
46 | (respectively). This option generates absolute relocations against the | |
47 | target symbols and is not appropriate for position-independent code. | |
48 | ||
49 | @cindex @code{no-relax} command line option, Nios II | |
50 | @item -no-relax | |
51 | Do not replace any branches or calls. | |
52 | ||
53 | @cindex @code{EB} command line option, Nios II | |
54 | @item -EB | |
55 | Generate big-endian output. | |
56 | ||
57 | @cindex @code{EL} command line option, Nios II | |
58 | @item -EL | |
59 | Generate little-endian output. This is the default. | |
60 | ||
61 | @end table | |
62 | @c man end | |
63 | ||
64 | @node Nios II Syntax | |
65 | @section Syntax | |
66 | @menu | |
67 | * Nios II Chars:: Special Characters | |
68 | @end menu | |
69 | ||
70 | ||
71 | @node Nios II Chars | |
72 | @subsection Special Characters | |
73 | ||
74 | @cindex line comment character, Nios II | |
75 | @cindex Nios II line comment character | |
76 | @cindex line separator character, Nios II | |
77 | @cindex Nios II line separator character | |
78 | @samp{#} is the line comment character. | |
79 | @samp{;} is the line separator character. | |
80 | ||
81 | ||
82 | @node Nios II Relocations | |
83 | @section Nios II Machine Relocations | |
84 | ||
85 | @cindex machine relocations, Nios II | |
86 | @cindex Nios II machine relocations | |
87 | ||
88 | @table @code | |
89 | @cindex @code{hiadj} directive, Nios II | |
90 | @item %hiadj(@var{expression}) | |
91 | Extract the upper 16 bits of @var{expression} and add | |
92 | one if the 15th bit is set. | |
93 | ||
94 | The value of @code{%hiadj(@var{expression})} is: | |
95 | @smallexample | |
96 | ((@var{expression} >> 16) & 0xffff) + ((@var{expression} >> 15) & 0x01) | |
97 | @end smallexample | |
98 | ||
99 | The @code{%hiadj} relocation is intended to be used with | |
100 | the @code{addi}, @code{ld} or @code{st} instructions | |
101 | along with a @code{%lo}, in order to load a 32-bit constant. | |
102 | ||
103 | @smallexample | |
104 | movhi r2, %hiadj(symbol) | |
105 | addi r2, r2, %lo(symbol) | |
106 | @end smallexample | |
107 | ||
108 | @cindex @code{hi} directive, Nios II | |
109 | @item %hi(@var{expression}) | |
110 | Extract the upper 16 bits of @var{expression}. | |
111 | ||
112 | @cindex @code{lo} directive, Nios II | |
113 | @item %lo(@var{expression}) | |
114 | Extract the lower 16 bits of @var{expression}. | |
115 | ||
116 | @cindex @code{gprel} directive, Nios II | |
117 | @item %gprel(@var{expression}) | |
118 | Subtract the value of the symbol @code{_gp} from | |
119 | @var{expression}. | |
120 | ||
121 | The intention of the @code{%gprel} relocation is | |
122 | to have a fast small area of memory which only | |
123 | takes a 16-bit immediate to access. | |
124 | ||
125 | @smallexample | |
126 | .section .sdata | |
127 | fastint: | |
128 | .int 123 | |
129 | .section .text | |
130 | ldw r4, %gprel(fastint)(gp) | |
131 | @end smallexample | |
132 | ||
133 | @cindex @code{call} directive, Nios II | |
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134 | @cindex @code{call_lo} directive, Nios II |
135 | @cindex @code{call_hiadj} directive, Nios II | |
36591ba1 | 136 | @cindex @code{got} directive, Nios II |
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137 | @cindex @code{got_lo} directive, Nios II |
138 | @cindex @code{got_hiadj} directive, Nios II | |
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139 | @cindex @code{gotoff} directive, Nios II |
140 | @cindex @code{gotoff_lo} directive, Nios II | |
141 | @cindex @code{gotoff_hiadj} directive, Nios II | |
142 | @cindex @code{tls_gd} directive, Nios II | |
143 | @cindex @code{tls_ie} directive, Nios II | |
144 | @cindex @code{tls_le} directive, Nios II | |
145 | @cindex @code{tls_ldm} directive, Nios II | |
146 | @cindex @code{tls_ldo} directive, Nios II | |
147 | @item %call(@var{expression}) | |
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148 | @item %call_lo(@var{expression}) |
149 | @item %call_hiadj(@var{expression}) | |
36591ba1 | 150 | @itemx %got(@var{expression}) |
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151 | @itemx %got_lo(@var{expression}) |
152 | @itemx %got_hiadj(@var{expression}) | |
36591ba1 SL |
153 | @itemx %gotoff(@var{expression}) |
154 | @itemx %gotoff_lo(@var{expression}) | |
155 | @itemx %gotoff_hiadj(@var{expression}) | |
156 | @itemx %tls_gd(@var{expression}) | |
157 | @itemx %tls_ie(@var{expression}) | |
158 | @itemx %tls_le(@var{expression}) | |
159 | @itemx %tls_ldm(@var{expression}) | |
160 | @itemx %tls_ldo(@var{expression}) | |
161 | ||
162 | These relocations support the ABI for Linux Systems documented in the | |
163 | @cite{Nios II Processor Reference Handbook}. | |
164 | @end table | |
165 | ||
166 | ||
167 | @node Nios II Directives | |
168 | @section Nios II Machine Directives | |
169 | ||
170 | @cindex machine directives, Nios II | |
171 | @cindex Nios II machine directives | |
172 | ||
173 | @table @code | |
174 | ||
175 | @cindex @code{align} directive, Nios II | |
176 | @item .align @var{expression} [, @var{expression}] | |
177 | This is the generic @code{.align} directive, however | |
178 | this aligns to a power of two. | |
179 | ||
180 | @cindex @code{half} directive, Nios II | |
181 | @item .half @var{expression} | |
182 | Create an aligned constant 2 bytes in size. | |
183 | ||
184 | @cindex @code{word} directive, Nios II | |
185 | @item .word @var{expression} | |
186 | Create an aligned constant 4 bytes in size. | |
187 | ||
188 | @cindex @code{dword} directive, Nios II | |
189 | @item .dword @var{expression} | |
190 | Create an aligned constant 8 bytes in size. | |
191 | ||
192 | @cindex @code{2byte} directive, Nios II | |
193 | @item .2byte @var{expression} | |
194 | Create an unaligned constant 2 bytes in size. | |
195 | ||
196 | @cindex @code{4byte} directive, Nios II | |
197 | @item .4byte @var{expression} | |
198 | Create an unaligned constant 4 bytes in size. | |
199 | ||
200 | @cindex @code{8byte} directive, Nios II | |
201 | @item .8byte @var{expression} | |
202 | Create an unaligned constant 8 bytes in size. | |
203 | ||
204 | @cindex @code{16byte} directive, Nios II | |
205 | @item .16byte @var{expression} | |
206 | Create an unaligned constant 16 bytes in size. | |
207 | ||
208 | @cindex @code{set noat} directive, Nios II | |
209 | @item .set noat | |
210 | Allows assembly code to use @code{at} register without | |
211 | warning. Macro or relaxation expansions | |
212 | generate warnings. | |
213 | ||
214 | @cindex @code{set at} directive, Nios II | |
215 | @item .set at | |
216 | Assembly code using @code{at} register generates | |
217 | warnings, and macro expansion and relaxation are | |
218 | enabled. | |
219 | ||
220 | @cindex @code{set nobreak} directive, Nios II | |
221 | @item .set nobreak | |
222 | Allows assembly code to use @code{ba} and @code{bt} | |
223 | registers without warning. | |
224 | ||
225 | @cindex @code{set break} directive, Nios II | |
226 | @item .set break | |
227 | Turns warnings back on for using @code{ba} and @code{bt} | |
228 | registers. | |
229 | ||
230 | @cindex @code{set norelax} directive, Nios II | |
231 | @item .set norelax | |
232 | Do not replace any branches or calls. | |
233 | ||
234 | @cindex @code{set relaxsection} directive, Nios II | |
235 | @item .set relaxsection | |
236 | Replace identified out-of-range branches with | |
237 | @code{jmp} sequences (default). | |
238 | ||
239 | @cindex @code{set relaxall} directive, Nios II | |
240 | @item .set relaxsection | |
241 | Replace all branch and call instructions with | |
242 | @code{jmp} and @code{callr} sequences. | |
243 | ||
244 | @cindex @code{set} directive, Nios II | |
245 | @item .set @dots{} | |
246 | All other @code{.set} are the normal use. | |
247 | ||
248 | @end table | |
249 | ||
250 | @node Nios II Opcodes | |
251 | @section Opcodes | |
252 | ||
253 | @cindex Nios II opcodes | |
254 | @cindex opcodes for Nios II | |
255 | @code{@value{AS}} implements all the standard Nios II opcodes documented in the | |
256 | @cite{Nios II Processor Reference Handbook}, including the assembler | |
257 | pseudo-instructions. |