Commit | Line | Data |
---|---|---|
3c9b82ba NC |
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 | ||
10 | @c DO-NOT-COMMIT | |
11 | ||
12 | @ifclear GENERIC | |
13 | @node Machine Dependencies | |
14 | @chapter Z80 Dependent Features | |
15 | @end ifclear | |
16 | ||
17 | @cindex Z80 support | |
18 | @menu | |
19 | * Z80 Options:: Options | |
20 | * Z80 Syntax:: Syntax | |
21 | * Z80 Floating Point:: Floating Point | |
22 | * Z80 Directives:: Z80 Machine Directives | |
23 | * Z80 Opcodes:: Opcodes | |
24 | @end menu | |
25 | ||
26 | @node Z80 Options | |
27 | @section Options | |
28 | @cindex Z80 options | |
29 | @cindex options for Z80 | |
30 | The Zilog Z80 and Ascii R800 version of @code{@value{AS}} have a few machine | |
31 | dependent options. | |
32 | @table @option | |
33 | @cindex @code{-z80} command line option, Z80 | |
34 | @item -z80 | |
35 | Produce code for the Z80 processor. There are additional options to | |
36 | request warnings and error messages for undocumented instructions. | |
37 | @item -ignore-undocumented-instructions | |
38 | @itemx -Wnud | |
39 | Silently assemble undocumented Z80-instructions that have been adopted | |
40 | as documented R800-instructions. | |
41 | @item -ignore-unportable-instructions | |
42 | @itemx -Wnup | |
43 | Silently assemble all undocumented Z80-instructions. | |
44 | @item -warn-undocumented-instructions | |
45 | @itemx -Wud | |
46 | Issue warnings for undocumented Z80-instructions that work on R800, do | |
47 | not assemble other undocumented instructions without warning. | |
48 | @item -warn-unportable-instructions | |
49 | @itemx -Wup | |
50 | Issue warnings for other undocumented Z80-instructions, do not treat any | |
51 | undocumented instructions as errors. | |
52 | @item -forbid-undocumented-instructions | |
53 | @itemx -Fud | |
54 | Treat all undocumented z80-instructions as errors. | |
55 | @item -forbid-unportable-instructions | |
56 | @itemx -Fup | |
57 | Treat undocumented z80-instructions that do not work on R800 as errors. | |
58 | ||
59 | @cindex @code{-r800} command line option, Z80 | |
60 | @item -r800 | |
61 | Produce code for the R800 processor. The assembler does not support | |
62 | undocumented instructions for the R800. | |
63 | In line with common practice, @code{@value{AS}} uses Z80 instriction names | |
64 | for the R800 processor, as far as they exist. | |
65 | @end table | |
66 | ||
67 | @cindex Z80 Syntax | |
68 | @node Z80 Syntax | |
69 | @section Syntax | |
70 | The assembler syntax closely follows the 'Z80 family CPU User Manual' by | |
71 | Zilog. | |
72 | In expressions a single @samp{=} may be used as ``is equal to'' | |
73 | comparison operator. | |
74 | ||
75 | Suffices can be used to indicate the radix of integer constants; | |
76 | @samp{H} or @samp{h} for hexadecimal, @samp{D} or @samp{d} for decimal, | |
77 | @samp{Q}, @samp{O}, @samp{q} or @samp{o} for octal, and @samp{B} for | |
78 | binary. | |
79 | ||
80 | The suffix @samp{b} denotes a backreference to local label. | |
81 | ||
82 | @menu | |
83 | * Z80-Chars:: Special Characters | |
84 | * Z80-Regs:: Register Names | |
85 | * Z80-Case:: Case Sensitivity | |
86 | @end menu | |
87 | ||
88 | @node Z80-Chars | |
89 | @subsection Special Characters | |
90 | ||
91 | @cindex line comment character, Z80 | |
92 | @cindex Z80 line comment character | |
93 | The semicolon @samp{;} is the line comment character; | |
94 | ||
95 | @cindex location counter, Z80 | |
96 | @cindex hexadecimal prefix, Z80 | |
97 | @cindex Z80 $ | |
98 | The dollar sign @samp{$} can be used as a prefix for hexadecimal numbers | |
99 | and as a symbol denoting the current location counter. | |
100 | ||
101 | @cindex character escapes, Z80 | |
102 | @cindex Z80, \ | |
103 | A backslash @samp{\} is an ordinary character for the Z80 assembler. | |
104 | ||
105 | @cindex character constant, Z80 | |
106 | @cindex single quote, Z80 | |
107 | @cindex Z80 ' | |
108 | The single quote @samp{'} must be followed by a closing quote. If there | |
109 | is one character inbetween, it is a character constant, otherwise it is | |
110 | a string constant. | |
111 | ||
112 | @node Z80-Regs | |
113 | @subsection Register Names | |
114 | @cindex Z80 registers | |
115 | @cindex register names, Z80 | |
116 | ||
117 | The registers are referred to with the letters assigned to them by | |
118 | Zilog. In addition @command{@value{AS}} recognises @samp{ixl} and | |
119 | @samp{ixh} as the least and most significant octet in @samp{ix}, and | |
120 | similarly @samp{iyl} and @samp{iyh} as parts of @samp{iy}. | |
121 | ||
122 | @c The @samp{'} in @samp{ex af,af'} may be omitted. | |
123 | ||
124 | @node Z80-Case | |
125 | @subsection Case Sensitivity | |
126 | @cindex Z80, case sensitivity | |
127 | @cindex case sensitivity, Z80 | |
128 | ||
129 | Upper and lower case are equivalent in register names, opcodes, | |
130 | condition codes and assembler directives. | |
131 | The case of letters is significant in labels and symbol names. The case | |
132 | is also important to distinguish the suffix @samp{b} for a backward reference | |
133 | to a local label from the suffix @samp{B} for a number in binary notation. | |
134 | ||
135 | @node Z80 Floating Point | |
136 | @section Floating Point | |
137 | @cindex floating point, Z80 | |
138 | @cindex Z80 floating point | |
139 | Floating-point numbers are not supported. | |
140 | ||
141 | @node Z80 Directives | |
142 | @section Z80 Assembler Directives | |
143 | ||
144 | @command{@value{AS}} for the Z80 supports some additional directives for | |
145 | compatibility with other assemblers. | |
146 | ||
147 | @cindex Z80-only directives | |
148 | These are the additional directives in @code{@value{AS}} for the Z80: | |
149 | ||
150 | @table @code | |
151 | @item db @var{expression}|@var{string}[,@var{expression}|@var{string}...] | |
152 | @itemx defb @var{expression}|@var{string}[,@var{expression}|@var{string}...] | |
153 | For each @var{string} the characters are copied to the object file, for | |
154 | each other @var{expression} the value is stored in one byte, ignoring | |
155 | overflow. | |
156 | ||
157 | @item dw @var{expression}[,@var{expression}...] | |
158 | @itemx defw @var{expression}[,@var{expression}...] | |
159 | For each @var{expression} the value is stored in two bytes, ignoring | |
160 | overflow. | |
161 | ||
162 | @item ds @var{count}[, @var{value}] | |
163 | @itemx defs @var{count}[, @var{value}] | |
164 | @c Synonyms for @code{ds.b}, | |
165 | @c which should have been described elsewhre | |
166 | Fill @var{count} bytes in the object file with @var{value}, if | |
167 | @var{value} is omitted it defaults to zero. | |
168 | ||
169 | @item @var{symbol} equ @var{expression} | |
170 | @itemx @var{symbol} defl @var{expression} | |
171 | These directives set the value of @var{symbol} to @var{expression}. To | |
172 | keep code portable to other assemblers it is best to use @samp{equ} for | |
173 | the first definition and @samp{defl} for redefinitions. | |
174 | ||
175 | @item set | |
176 | This is a normal instruction on Z80, and not an assembler directive. | |
177 | ||
178 | @item psect @var{name} | |
179 | A synonym for @xref{Section}, no second argument should be given. | |
180 | @ignore | |
181 | ||
182 | The following attributes will possibly be recognised in the future | |
183 | @table @code | |
184 | @item abs | |
185 | The section is to be absolute. @code{@value{AS}} will issue an error | |
186 | message because it can not produce an absolute section. | |
187 | @item global | |
188 | The section is to be concatenated with other sections of the same name | |
189 | by the linker, this is the default. | |
190 | @item local | |
191 | The section is not global. @code{@value{AS}} will issue a warning if | |
192 | object file format is not soff. | |
193 | @item ovrld | |
194 | The section is to be overlapped with other sections of the same name by | |
195 | the linker. @code{@value{AS}} will issue an error message | |
196 | because it can not mark a section as such. | |
197 | @item pure | |
198 | The section is marked as read only. | |
199 | @end table | |
200 | @end ignore | |
201 | ||
202 | @end table | |
203 | ||
204 | @node Z80 Opcodes | |
205 | @section Opcodes | |
206 | In line with commmon practice Z80 mnonics are used for both the Z80 and | |
207 | the R800. | |
208 | ||
209 | In many instructions it is possible to use one of the half index | |
210 | registers (@samp{ixl},@samp{ixh},@samp{iyl},@samp{iyh}) in stead of an | |
211 | 8-bit general purpose register. This yields instructions that are | |
212 | documented on the R800 and undocumented on the Z80. | |
213 | Similarly @code{in f,(c)} is documented on the R800 and undocumented on | |
214 | the Z80. | |
215 | ||
216 | The assembler also supports the following undocumented Z80-instructions, | |
217 | that have not been adopted in the R800 instruction set: | |
218 | @table @code | |
219 | @item out (c),0 | |
220 | Sends zero to the port pointed to by register c. | |
221 | ||
222 | @item sli @var{m} | |
223 | Equivalent to @code{@var{m} = (@var{m}<<1)+1}, the operand @var{m} can | |
224 | be any operand that is valid for @samp{sla}. One can use @samp{sll} as a | |
225 | synonym for @samp{sli}. | |
226 | ||
227 | @item @var{op} (ix+@var{d}), @var{r} | |
228 | This is equivalent to | |
229 | ||
230 | @example | |
231 | ld @var{r}, (ix+@var{d}) | |
232 | @var{opc} @var{r} | |
233 | ld (ix+@var{d}), @var{r} | |
234 | @end example | |
235 | ||
236 | The operation @samp{@var{opc}} may be any of @samp{res @var{b},}, | |
237 | @samp{set @var{b},}, @samp{rl}, @samp{rlc}, @samp{rr}, @samp{rrc}, | |
238 | @samp{sla}, @samp{sli}, @samp{sra} and @samp{srl}, and the register | |
239 | @samp{@var{r}} may be any of @samp{a}, @samp{b}, @samp{c}, @samp{d}, | |
240 | @samp{e}, @samp{h} and @samp{l}. | |
241 | ||
242 | @item @var{opc} (iy+@var{d}), @var{r} | |
243 | As above, but with @samp{iy} instead of @samp{ix}. | |
244 | @end table | |
245 | ||
246 | The web site at @uref{http://www.z80.info} is a good starting place to | |
247 | find more information on programming the Z80. | |
248 |