gas/doc/c-rx.texi

   1 @c Copyright (C) 2008-2015 Free Software Foundation, Inc.
   2 @c This is part of the GAS manual.
   3 @c For copying conditions, see the file as.texinfo.
   4 @ifset GENERIC
   5 @page
   6 @node RX-Dependent
   7 @chapter RX Dependent Features
   8 @end ifset
   9 @ifclear GENERIC
  10 @node Machine Dependencies
  11 @chapter RX Dependent Features
  12 @end ifclear
  13
  14 @cindex RX support
  15 @menu
  16 * RX-Opts::                   RX Assembler Command Line Options
  17 * RX-Modifiers::              Symbolic Operand Modifiers
  18 * RX-Directives::             Assembler Directives
  19 * RX-Float::                  Floating Point
  20 * RX-Syntax::                 Syntax
  21 @end menu
  22
  23 @node RX-Opts
  24 @section RX Options
  25 @cindex options, RX
  26 @cindex RX options
  27
  28 The Renesas RX port of @code{@value{AS}} has a few target specfic
  29 command line options:
  30
  31 @table @code
  32
  33 @cindex @samp{-m32bit-doubles}
  34 @item -m32bit-doubles
  35 This option controls the ABI and indicates to use a 32-bit float ABI.
  36 It has no effect on the assembled instructions, but it does influence
  37 the behaviour of the @samp{.double} pseudo-op.
  38 This is the default.
  39
  40 @cindex @samp{-m64bit-doubles}
  41 @item -m64bit-doubles
  42 This option controls the ABI and indicates to use a 64-bit float ABI.
  43 It has no effect on the assembled instructions, but it does influence
  44 the behaviour of the @samp{.double} pseudo-op.
  45
  46 @cindex @samp{-mbig-endian}
  47 @item -mbig-endian
  48 This option controls the ABI and indicates to use a big-endian data
  49 ABI.  It has no effect on the assembled instructions, but it does
  50 influence the behaviour of the @samp{.short}, @samp{.hword}, @samp{.int},
  51 @samp{.word}, @samp{.long}, @samp{.quad} and @samp{.octa} pseudo-ops.
  52
  53 @cindex @samp{-mlittle-endian}
  54 @item -mlittle-endian
  55 This option controls the ABI and indicates to use a little-endian data
  56 ABI.  It has no effect on the assembled instructions, but it does
  57 influence the behaviour of the @samp{.short}, @samp{.hword}, @samp{.int},
  58 @samp{.word}, @samp{.long}, @samp{.quad} and @samp{.octa} pseudo-ops.
  59 This is the default.
  60
  61 @cindex @samp{-muse-conventional-section-names}
  62 @item -muse-conventional-section-names
  63 This option controls the default names given to the code (.text),
  64 initialised data (.data) and uninitialised data sections (.bss).
  65
  66 @cindex @samp{-muse-renesas-section-names}
  67 @item -muse-renesas-section-names
  68 This option controls the default names given to the code (.P),
  69 initialised data (.D_1) and uninitialised data sections (.B_1).
  70 This is the default.
  71
  72 @cindex @samp{-msmall-data-limit}
  73 @item -msmall-data-limit
  74 This option tells the assembler that the small data limit feature of
  75 the RX port of GCC is being used.  This results in the assembler
  76 generating an undefined reference to a symbol called @code{__gp} for
  77 use by the relocations that are needed to support the small data limit
  78 feature.   This option is not enabled by default as it would otherwise
  79 pollute the symbol table.
  80
  81 @cindex @samp{-mpid}
  82 @item -mpid
  83 This option tells the assembler that the position independent data of the
  84 RX port of GCC is being used.  This results in the assembler
  85 generating an undefined reference to a symbol called @code{__pid_base},
  86 and also setting the RX_PID flag bit in the e_flags field of the ELF
  87 header of the object file.
  88
  89 @cindex @samp{-mint-register}
  90 @item -mint-register=@var{num}
  91 This option tells the assembler how many registers have been reserved
  92 for use by interrupt handlers.  This is needed in order to compute the
  93 correct values for the @code{%gpreg} and @code{%pidreg} meta registers.
  94
  95 @cindex @samp{-mgcc-abi}
  96 @item -mgcc-abi
  97 This option tells the assembler that the old GCC ABI is being used by
  98 the assembled code.  With this version of the ABI function arguments
  99 that are passed on the stack are aligned to a 32-bit boundary.
 100
 101 @cindex @samp{-mrx-abi}
 102 @item -mrx-abi
 103 This option tells the assembler that the official RX ABI is being used
 104 by the assembled code.  With this version of the ABI function
 105 arguments that are passed on the stack are aligned to their natural
 106 alignments.  This option is the default.
 107
 108 @cindex @samp{-mcpu=}
 109 @item -mcpu=@var{name}
 110 This option tells the assembler the target CPU type.  Currently the
 111 @code{rx200}, @code{rx600} and @code{rx610} are recognised as valid
 112 cpu names.  Attempting to assemble an instruction not supported by the
 113 indicated cpu type will result in an error message being generated.
 114
 115 @cindex @samp{-mno-allow-string-insns}
 116 @item -mno-allow-string-insns
 117 This option tells the assembler to mark the object file that it is
 118 building as one that does not use the string instructions
 119 @code{SMOVF}, @code{SCMPU}, @code {SMOVB}, @code{SMOVU}, @code{SUNTIL}
 120 @code {SWHILE} or the @code {RMPA} instruction.  In addition the mark
 121 tells the linker to complain if an attempt is made to link the binary
 122 with another one that does use any of these instructions.
 123
 124 Note - the inverse of this option, @code{-mallow-string-insns}, is
 125 not needed.  The assembler automatically detects the use of the
 126 the instructions in the source code and labels the resulting
 127 object file appropriately.  If no string instructions are detected
 128 then the object file is labelled as being one that can be linked with
 129 either string-using or string-banned object files.
 130 @end table
 131
 132 @node RX-Modifiers
 133 @section Symbolic Operand Modifiers
 134
 135 @cindex RX modifiers
 136 @cindex syntax, RX
 137 @cindex %gp
 138
 139 The assembler supports one modifier when using symbol addresses
 140 in RX instruction operands.  The general syntax is the following:
 141
 142 @smallexample
 143 %gp(symbol)
 144 @end smallexample
 145
 146 The modifier returns the offset from the @var{__gp} symbol to the
 147 specified symbol as a 16-bit value.  The intent is that this offset
 148 should be used in a register+offset move instruction when generating
 149 references to small data.  Ie, like this:
 150
 151 @smallexample
 152   mov.W  %gp(_foo)[%gpreg], r1
 153 @end smallexample
 154
 155 The assembler also supports two meta register names which can be used
 156 to refer to registers whose values may not be known to the
 157 programmer.  These meta register names are:
 158
 159 @table @code
 160
 161 @cindex @samp{%gpreg}
 162 @item %gpreg
 163 The small data address register.
 164
 165 @cindex @samp{%pidreg}
 166 @item %pidreg
 167 The PID base address register.
 168
 169 @end table
 170
 171 Both registers normally have the value r13, but this can change if
 172 some registers have been reserved for use by interrupt handlers or if
 173 both the small data limit and position independent data features are
 174 being used at the same time.
 175
 176 @node RX-Directives
 177 @section Assembler Directives
 178
 179 @cindex assembler directives, RX
 180 @cindex RX assembler directives
 181
 182 The RX version of @code{@value{AS}} has the following specific
 183 assembler directives:
 184
 185 @table @code
 186
 187 @item .3byte
 188 @cindex assembler directive .3byte, RX
 189 @cindex RX assembler directive .3byte
 190 Inserts a 3-byte value into the output file at the current location.
 191
 192 @item .fetchalign
 193 @cindex assembler directive .fetchalign, RX
 194 @cindex RX assembler directive .fetchalign
 195 If the next opcode following this directive spans a fetch line
 196 boundary (8 byte boundary), the opcode is aligned to that boundary.
 197 If the next opcode does not span a fetch line, this directive has no
 198 effect.  Note that one or more labels may be between this directive
 199 and the opcode; those labels are aligned as well.  Any inserted bytes
 200 due to alignment will form a NOP opcode.
 201
 202 @end table
 203
 204 @node RX-Float
 205 @section Floating Point
 206
 207 @cindex floating point, RX
 208 @cindex RX floating point
 209
 210 The floating point formats generated by directives are these.
 211
 212 @table @code
 213 @cindex @code{float} directive, RX
 214
 215 @item .float
 216 @code{Single} precision (32-bit) floating point constants.
 217
 218 @cindex @code{double} directive, RX
 219 @item .double
 220 If the @option{-m64bit-doubles} command line option has been specified
 221 then then @code{double} directive generates @code{double} precision
 222 (64-bit) floating point constants, otherwise it generates
 223 @code{single} precision (32-bit) floating point constants.  To force
 224 the generation of 64-bit floating point constants used the @code{dc.d}
 225 directive instead.
 226
 227 @end table
 228
 229 @node RX-Syntax
 230 @section Syntax for the RX
 231 @menu
 232 * RX-Chars::                Special Characters
 233 @end menu
 234
 235 @node RX-Chars
 236 @subsection Special Characters
 237
 238 @cindex line comment character, RX
 239 @cindex RX line comment character
 240 The presence of a @samp{;} appearing anywhere on a line indicates the
 241 start of a comment that extends to the end of that line.
 242
 243 If a @samp{#} appears as the first character of a line then the whole
 244 line is treated as a comment, but in this case the line can also be a
 245 logical line number directive (@pxref{Comments}) or a preprocessor
 246 control command (@pxref{Preprocessing}).
 247
 248 @cindex line separator, RX
 249 @cindex statement separator, RX
 250 @cindex RX line separator
 251 The @samp{!} character can be used to separate statements on the same
 252 line.