| 1 | @c Copyright (C) 2011-2015 Free Software Foundation, Inc. |
| 2 | @c This is part of the GAS manual. |
| 3 | @c For copying conditions, see the file as.texinfo. |
| 4 | |
| 5 | @ifset GENERIC |
| 6 | @page |
| 7 | @node Z80-Dependent |
| 8 | @chapter Z80 Dependent Features |
| 9 | @end ifset |
| 10 | |
| 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 instruction 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 | If a @samp{#} appears as the first character of a line then the whole |
| 96 | line is treated as a comment, but in this case the line could also be |
| 97 | a logical line number directive (@pxref{Comments}) or a preprocessor |
| 98 | control command (@pxref{Preprocessing}). |
| 99 | |
| 100 | @cindex line separator, Z80 |
| 101 | @cindex statement separator, Z80 |
| 102 | @cindex Z80 line separator |
| 103 | The Z80 assembler does not support a line separator character. |
| 104 | |
| 105 | @cindex location counter, Z80 |
| 106 | @cindex hexadecimal prefix, Z80 |
| 107 | @cindex Z80 $ |
| 108 | The dollar sign @samp{$} can be used as a prefix for hexadecimal numbers |
| 109 | and as a symbol denoting the current location counter. |
| 110 | |
| 111 | @cindex character escapes, Z80 |
| 112 | @cindex Z80, \ |
| 113 | A backslash @samp{\} is an ordinary character for the Z80 assembler. |
| 114 | |
| 115 | @cindex character constant, Z80 |
| 116 | @cindex single quote, Z80 |
| 117 | @cindex Z80 ' |
| 118 | The single quote @samp{'} must be followed by a closing quote. If there |
| 119 | is one character in between, it is a character constant, otherwise it is |
| 120 | a string constant. |
| 121 | |
| 122 | @node Z80-Regs |
| 123 | @subsection Register Names |
| 124 | @cindex Z80 registers |
| 125 | @cindex register names, Z80 |
| 126 | |
| 127 | The registers are referred to with the letters assigned to them by |
| 128 | Zilog. In addition @command{@value{AS}} recognizes @samp{ixl} and |
| 129 | @samp{ixh} as the least and most significant octet in @samp{ix}, and |
| 130 | similarly @samp{iyl} and @samp{iyh} as parts of @samp{iy}. |
| 131 | |
| 132 | @c The @samp{'} in @samp{ex af,af'} may be omitted. |
| 133 | |
| 134 | @node Z80-Case |
| 135 | @subsection Case Sensitivity |
| 136 | @cindex Z80, case sensitivity |
| 137 | @cindex case sensitivity, Z80 |
| 138 | |
| 139 | Upper and lower case are equivalent in register names, opcodes, |
| 140 | condition codes and assembler directives. |
| 141 | The case of letters is significant in labels and symbol names. The case |
| 142 | is also important to distinguish the suffix @samp{b} for a backward reference |
| 143 | to a local label from the suffix @samp{B} for a number in binary notation. |
| 144 | |
| 145 | @node Z80 Floating Point |
| 146 | @section Floating Point |
| 147 | @cindex floating point, Z80 |
| 148 | @cindex Z80 floating point |
| 149 | Floating-point numbers are not supported. |
| 150 | |
| 151 | @node Z80 Directives |
| 152 | @section Z80 Assembler Directives |
| 153 | |
| 154 | @command{@value{AS}} for the Z80 supports some additional directives for |
| 155 | compatibility with other assemblers. |
| 156 | |
| 157 | @cindex Z80-only directives |
| 158 | These are the additional directives in @code{@value{AS}} for the Z80: |
| 159 | |
| 160 | @table @code |
| 161 | @item db @var{expression}|@var{string}[,@var{expression}|@var{string}...] |
| 162 | @itemx defb @var{expression}|@var{string}[,@var{expression}|@var{string}...] |
| 163 | For each @var{string} the characters are copied to the object file, for |
| 164 | each other @var{expression} the value is stored in one byte. |
| 165 | A warning is issued in case of an overflow. |
| 166 | |
| 167 | @item dw @var{expression}[,@var{expression}...] |
| 168 | @itemx defw @var{expression}[,@var{expression}...] |
| 169 | For each @var{expression} the value is stored in two bytes, ignoring |
| 170 | overflow. |
| 171 | |
| 172 | @item d24 @var{expression}[,@var{expression}...] |
| 173 | @itemx def24 @var{expression}[,@var{expression}...] |
| 174 | For each @var{expression} the value is stored in three bytes, ignoring |
| 175 | overflow. |
| 176 | |
| 177 | @item d32 @var{expression}[,@var{expression}...] |
| 178 | @itemx def32 @var{expression}[,@var{expression}...] |
| 179 | For each @var{expression} the value is stored in four bytes, ignoring |
| 180 | overflow. |
| 181 | |
| 182 | @item ds @var{count}[, @var{value}] |
| 183 | @itemx defs @var{count}[, @var{value}] |
| 184 | @c Synonyms for @code{ds.b}, |
| 185 | @c which should have been described elsewhere |
| 186 | Fill @var{count} bytes in the object file with @var{value}, if |
| 187 | @var{value} is omitted it defaults to zero. |
| 188 | |
| 189 | @item @var{symbol} equ @var{expression} |
| 190 | @itemx @var{symbol} defl @var{expression} |
| 191 | These directives set the value of @var{symbol} to @var{expression}. If |
| 192 | @code{equ} is used, it is an error if @var{symbol} is already defined. |
| 193 | Symbols defined with @code{equ} are not protected from redefinition. |
| 194 | |
| 195 | @item set |
| 196 | This is a normal instruction on Z80, and not an assembler directive. |
| 197 | |
| 198 | @item psect @var{name} |
| 199 | A synonym for @xref{Section}, no second argument should be given. |
| 200 | @ignore |
| 201 | |
| 202 | The following attributes will possibly be recognized in the future |
| 203 | @table @code |
| 204 | @item abs |
| 205 | The section is to be absolute. @code{@value{AS}} will issue an error |
| 206 | message because it can not produce an absolute section. |
| 207 | @item global |
| 208 | The section is to be concatenated with other sections of the same name |
| 209 | by the linker, this is the default. |
| 210 | @item local |
| 211 | The section is not global. @code{@value{AS}} will issue a warning if |
| 212 | object file format is not soff. |
| 213 | @item ovrld |
| 214 | The section is to be overlapped with other sections of the same name by |
| 215 | the linker. @code{@value{AS}} will issue an error message |
| 216 | because it can not mark a section as such. |
| 217 | @item pure |
| 218 | The section is marked as read only. |
| 219 | @end table |
| 220 | @end ignore |
| 221 | |
| 222 | @end table |
| 223 | |
| 224 | @node Z80 Opcodes |
| 225 | @section Opcodes |
| 226 | In line with common practice, Z80 mnemonics are used for both the Z80 and |
| 227 | the R800. |
| 228 | |
| 229 | In many instructions it is possible to use one of the half index |
| 230 | registers (@samp{ixl},@samp{ixh},@samp{iyl},@samp{iyh}) in stead of an |
| 231 | 8-bit general purpose register. This yields instructions that are |
| 232 | documented on the R800 and undocumented on the Z80. |
| 233 | Similarly @code{in f,(c)} is documented on the R800 and undocumented on |
| 234 | the Z80. |
| 235 | |
| 236 | The assembler also supports the following undocumented Z80-instructions, |
| 237 | that have not been adopted in the R800 instruction set: |
| 238 | @table @code |
| 239 | @item out (c),0 |
| 240 | Sends zero to the port pointed to by register c. |
| 241 | |
| 242 | @item sli @var{m} |
| 243 | Equivalent to @code{@var{m} = (@var{m}<<1)+1}, the operand @var{m} can |
| 244 | be any operand that is valid for @samp{sla}. One can use @samp{sll} as a |
| 245 | synonym for @samp{sli}. |
| 246 | |
| 247 | @item @var{op} (ix+@var{d}), @var{r} |
| 248 | This is equivalent to |
| 249 | |
| 250 | @example |
| 251 | ld @var{r}, (ix+@var{d}) |
| 252 | @var{opc} @var{r} |
| 253 | ld (ix+@var{d}), @var{r} |
| 254 | @end example |
| 255 | |
| 256 | The operation @samp{@var{opc}} may be any of @samp{res @var{b},}, |
| 257 | @samp{set @var{b},}, @samp{rl}, @samp{rlc}, @samp{rr}, @samp{rrc}, |
| 258 | @samp{sla}, @samp{sli}, @samp{sra} and @samp{srl}, and the register |
| 259 | @samp{@var{r}} may be any of @samp{a}, @samp{b}, @samp{c}, @samp{d}, |
| 260 | @samp{e}, @samp{h} and @samp{l}. |
| 261 | |
| 262 | @item @var{opc} (iy+@var{d}), @var{r} |
| 263 | As above, but with @samp{iy} instead of @samp{ix}. |
| 264 | @end table |
| 265 | |
| 266 | The web site at @uref{http://www.z80.info} is a good starting place to |
| 267 | find more information on programming the Z80. |
| 268 | |