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1 | @c This is part of the GAS manual. |
2 | @c For copying conditions, see the file as.texinfo. | |
3 | ||
4 | @ifset GENERIC | |
5 | @page | |
6 | @node Z80-Dependent | |
7 | @chapter Z80 Dependent Features | |
8 | @end ifset | |
9 | ||
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10 | |
11 | @ifclear GENERIC | |
12 | @node Machine Dependencies | |
13 | @chapter Z80 Dependent Features | |
14 | @end ifclear | |
15 | ||
16 | @cindex Z80 support | |
17 | @menu | |
18 | * Z80 Options:: Options | |
19 | * Z80 Syntax:: Syntax | |
20 | * Z80 Floating Point:: Floating Point | |
21 | * Z80 Directives:: Z80 Machine Directives | |
22 | * Z80 Opcodes:: Opcodes | |
23 | @end menu | |
24 | ||
25 | @node Z80 Options | |
26 | @section Options | |
27 | @cindex Z80 options | |
28 | @cindex options for Z80 | |
29 | The Zilog Z80 and Ascii R800 version of @code{@value{AS}} have a few machine | |
30 | dependent options. | |
31 | @table @option | |
32 | @cindex @code{-z80} command line option, Z80 | |
33 | @item -z80 | |
34 | Produce code for the Z80 processor. There are additional options to | |
35 | request warnings and error messages for undocumented instructions. | |
36 | @item -ignore-undocumented-instructions | |
37 | @itemx -Wnud | |
38 | Silently assemble undocumented Z80-instructions that have been adopted | |
39 | as documented R800-instructions. | |
40 | @item -ignore-unportable-instructions | |
41 | @itemx -Wnup | |
42 | Silently assemble all undocumented Z80-instructions. | |
43 | @item -warn-undocumented-instructions | |
44 | @itemx -Wud | |
45 | Issue warnings for undocumented Z80-instructions that work on R800, do | |
46 | not assemble other undocumented instructions without warning. | |
47 | @item -warn-unportable-instructions | |
48 | @itemx -Wup | |
49 | Issue warnings for other undocumented Z80-instructions, do not treat any | |
50 | undocumented instructions as errors. | |
51 | @item -forbid-undocumented-instructions | |
52 | @itemx -Fud | |
53 | Treat all undocumented z80-instructions as errors. | |
54 | @item -forbid-unportable-instructions | |
55 | @itemx -Fup | |
56 | Treat undocumented z80-instructions that do not work on R800 as errors. | |
57 | ||
58 | @cindex @code{-r800} command line option, Z80 | |
59 | @item -r800 | |
60 | Produce code for the R800 processor. The assembler does not support | |
61 | undocumented instructions for the R800. | |
b45619c0 | 62 | In line with common practice, @code{@value{AS}} uses Z80 instruction names |
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63 | for the R800 processor, as far as they exist. |
64 | @end table | |
65 | ||
66 | @cindex Z80 Syntax | |
67 | @node Z80 Syntax | |
68 | @section Syntax | |
69 | The assembler syntax closely follows the 'Z80 family CPU User Manual' by | |
70 | Zilog. | |
71 | In expressions a single @samp{=} may be used as ``is equal to'' | |
72 | comparison operator. | |
73 | ||
74 | Suffices can be used to indicate the radix of integer constants; | |
75 | @samp{H} or @samp{h} for hexadecimal, @samp{D} or @samp{d} for decimal, | |
76 | @samp{Q}, @samp{O}, @samp{q} or @samp{o} for octal, and @samp{B} for | |
77 | binary. | |
78 | ||
79 | The suffix @samp{b} denotes a backreference to local label. | |
80 | ||
81 | @menu | |
82 | * Z80-Chars:: Special Characters | |
83 | * Z80-Regs:: Register Names | |
84 | * Z80-Case:: Case Sensitivity | |
85 | @end menu | |
86 | ||
87 | @node Z80-Chars | |
88 | @subsection Special Characters | |
89 | ||
90 | @cindex line comment character, Z80 | |
91 | @cindex Z80 line comment character | |
92 | The semicolon @samp{;} is the line comment character; | |
93 | ||
94 | @cindex location counter, Z80 | |
95 | @cindex hexadecimal prefix, Z80 | |
96 | @cindex Z80 $ | |
97 | The dollar sign @samp{$} can be used as a prefix for hexadecimal numbers | |
98 | and as a symbol denoting the current location counter. | |
99 | ||
100 | @cindex character escapes, Z80 | |
101 | @cindex Z80, \ | |
102 | A backslash @samp{\} is an ordinary character for the Z80 assembler. | |
103 | ||
104 | @cindex character constant, Z80 | |
105 | @cindex single quote, Z80 | |
106 | @cindex Z80 ' | |
107 | The single quote @samp{'} must be followed by a closing quote. If there | |
b45619c0 | 108 | is one character in between, it is a character constant, otherwise it is |
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109 | a string constant. |
110 | ||
111 | @node Z80-Regs | |
112 | @subsection Register Names | |
113 | @cindex Z80 registers | |
114 | @cindex register names, Z80 | |
115 | ||
116 | The registers are referred to with the letters assigned to them by | |
b45619c0 | 117 | Zilog. In addition @command{@value{AS}} recognizes @samp{ixl} and |
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118 | @samp{ixh} as the least and most significant octet in @samp{ix}, and |
119 | similarly @samp{iyl} and @samp{iyh} as parts of @samp{iy}. | |
120 | ||
121 | @c The @samp{'} in @samp{ex af,af'} may be omitted. | |
122 | ||
123 | @node Z80-Case | |
124 | @subsection Case Sensitivity | |
125 | @cindex Z80, case sensitivity | |
126 | @cindex case sensitivity, Z80 | |
127 | ||
128 | Upper and lower case are equivalent in register names, opcodes, | |
129 | condition codes and assembler directives. | |
130 | The case of letters is significant in labels and symbol names. The case | |
131 | is also important to distinguish the suffix @samp{b} for a backward reference | |
132 | to a local label from the suffix @samp{B} for a number in binary notation. | |
133 | ||
134 | @node Z80 Floating Point | |
135 | @section Floating Point | |
136 | @cindex floating point, Z80 | |
137 | @cindex Z80 floating point | |
138 | Floating-point numbers are not supported. | |
139 | ||
140 | @node Z80 Directives | |
141 | @section Z80 Assembler Directives | |
142 | ||
143 | @command{@value{AS}} for the Z80 supports some additional directives for | |
144 | compatibility with other assemblers. | |
145 | ||
146 | @cindex Z80-only directives | |
147 | These are the additional directives in @code{@value{AS}} for the Z80: | |
148 | ||
149 | @table @code | |
150 | @item db @var{expression}|@var{string}[,@var{expression}|@var{string}...] | |
151 | @itemx defb @var{expression}|@var{string}[,@var{expression}|@var{string}...] | |
152 | For each @var{string} the characters are copied to the object file, for | |
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153 | each other @var{expression} the value is stored in one byte. |
154 | A warning is issued in case of an overflow. | |
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155 | |
156 | @item dw @var{expression}[,@var{expression}...] | |
157 | @itemx defw @var{expression}[,@var{expression}...] | |
158 | For each @var{expression} the value is stored in two bytes, ignoring | |
159 | overflow. | |
160 | ||
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161 | @item d24 @var{expression}[,@var{expression}...] |
162 | @itemx def24 @var{expression}[,@var{expression}...] | |
163 | For each @var{expression} the value is stored in three bytes, ignoring | |
164 | overflow. | |
165 | ||
166 | @item d32 @var{expression}[,@var{expression}...] | |
167 | @itemx def32 @var{expression}[,@var{expression}...] | |
168 | For each @var{expression} the value is stored in four bytes, ignoring | |
169 | overflow. | |
170 | ||
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171 | @item ds @var{count}[, @var{value}] |
172 | @itemx defs @var{count}[, @var{value}] | |
173 | @c Synonyms for @code{ds.b}, | |
b45619c0 | 174 | @c which should have been described elsewhere |
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175 | Fill @var{count} bytes in the object file with @var{value}, if |
176 | @var{value} is omitted it defaults to zero. | |
177 | ||
178 | @item @var{symbol} equ @var{expression} | |
179 | @itemx @var{symbol} defl @var{expression} | |
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180 | These directives set the value of @var{symbol} to @var{expression}. If |
181 | @code{equ} is used, it is an error if @var{symbol} is already defined. | |
182 | Symbols defined with @code{equ} are not protected from redefinition. | |
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183 | |
184 | @item set | |
185 | This is a normal instruction on Z80, and not an assembler directive. | |
186 | ||
187 | @item psect @var{name} | |
188 | A synonym for @xref{Section}, no second argument should be given. | |
189 | @ignore | |
190 | ||
b45619c0 | 191 | The following attributes will possibly be recognized in the future |
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192 | @table @code |
193 | @item abs | |
194 | The section is to be absolute. @code{@value{AS}} will issue an error | |
195 | message because it can not produce an absolute section. | |
196 | @item global | |
197 | The section is to be concatenated with other sections of the same name | |
198 | by the linker, this is the default. | |
199 | @item local | |
200 | The section is not global. @code{@value{AS}} will issue a warning if | |
201 | object file format is not soff. | |
202 | @item ovrld | |
203 | The section is to be overlapped with other sections of the same name by | |
204 | the linker. @code{@value{AS}} will issue an error message | |
205 | because it can not mark a section as such. | |
206 | @item pure | |
207 | The section is marked as read only. | |
208 | @end table | |
209 | @end ignore | |
210 | ||
211 | @end table | |
212 | ||
213 | @node Z80 Opcodes | |
214 | @section Opcodes | |
b45619c0 | 215 | In line with common practice, Z80 mnemonics are used for both the Z80 and |
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216 | the R800. |
217 | ||
218 | In many instructions it is possible to use one of the half index | |
219 | registers (@samp{ixl},@samp{ixh},@samp{iyl},@samp{iyh}) in stead of an | |
220 | 8-bit general purpose register. This yields instructions that are | |
221 | documented on the R800 and undocumented on the Z80. | |
222 | Similarly @code{in f,(c)} is documented on the R800 and undocumented on | |
223 | the Z80. | |
224 | ||
225 | The assembler also supports the following undocumented Z80-instructions, | |
226 | that have not been adopted in the R800 instruction set: | |
227 | @table @code | |
228 | @item out (c),0 | |
229 | Sends zero to the port pointed to by register c. | |
230 | ||
231 | @item sli @var{m} | |
232 | Equivalent to @code{@var{m} = (@var{m}<<1)+1}, the operand @var{m} can | |
233 | be any operand that is valid for @samp{sla}. One can use @samp{sll} as a | |
234 | synonym for @samp{sli}. | |
235 | ||
236 | @item @var{op} (ix+@var{d}), @var{r} | |
237 | This is equivalent to | |
238 | ||
239 | @example | |
240 | ld @var{r}, (ix+@var{d}) | |
241 | @var{opc} @var{r} | |
242 | ld (ix+@var{d}), @var{r} | |
243 | @end example | |
244 | ||
245 | The operation @samp{@var{opc}} may be any of @samp{res @var{b},}, | |
246 | @samp{set @var{b},}, @samp{rl}, @samp{rlc}, @samp{rr}, @samp{rrc}, | |
247 | @samp{sla}, @samp{sli}, @samp{sra} and @samp{srl}, and the register | |
248 | @samp{@var{r}} may be any of @samp{a}, @samp{b}, @samp{c}, @samp{d}, | |
249 | @samp{e}, @samp{h} and @samp{l}. | |
250 | ||
251 | @item @var{opc} (iy+@var{d}), @var{r} | |
252 | As above, but with @samp{iy} instead of @samp{ix}. | |
253 | @end table | |
254 | ||
255 | The web site at @uref{http://www.z80.info} is a good starting place to | |
256 | find more information on programming the Z80. | |
257 |