1 @c Copyright (C) 2011-2016 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. 268 269
