gas/doc/c-msp430.texi

   1 @c Copyright 2002, 2004 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 MSP430-Dependent
   7 @chapter MSP 430 Dependent Features
   8 @end ifset
   9 @ifclear GENERIC
  10 @node Machine Dependencies
  11 @chapter MSP 430 Dependent Features
  12 @end ifclear
  13
  14 @cindex MSP 430 support
  15 @cindex 430 support
  16 @menu
  17 * MSP430 Options::              Options
  18 * MSP430 Syntax::               Syntax
  19 * MSP430 Floating Point::       Floating Point
  20 * MSP430 Directives::           MSP 430 Machine Directives
  21 * MSP430 Opcodes::              Opcodes
  22 * MSP430 Profiling Capability:: Profiling Capability
  23 @end menu
  24
  25 @node MSP430 Options
  26 @section Options
  27 @cindex MSP 430 options (none)
  28 @cindex options for MSP430 (none)
  29 @code{@value{AS}} has only -m flag which selects the mpu arch. Currently has
  30 no effect.
  31
  32 @node MSP430 Syntax
  33 @section Syntax
  34 @menu
  35 * MSP430-Macros::               Macros
  36 * MSP430-Chars::                Special Characters
  37 * MSP430-Regs::                 Register Names
  38 * MSP430-Ext::                  Assembler Extensions
  39 @end menu
  40
  41 @node MSP430-Macros
  42 @subsection Macros
  43
  44 @cindex Macros, MSP 430
  45 @cindex MSP 430 macros
  46 The macro syntax used on the MSP 430 is like that described in the MSP
  47 430 Family Assembler Specification.  Normal @code{@value{AS}}
  48 macros should still work.
  49
  50 Additional built-in macros are:
  51
  52 @table @code
  53
  54 @item llo(exp)
  55 Extracts least significant word from 32-bit expression 'exp'.
  56
  57 @item lhi(exp)
  58 Extracts most significant word from 32-bit expression 'exp'.
  59
  60 @item hlo(exp)
  61 Extracts 3rd word from 64-bit expression 'exp'.
  62
  63 @item   hhi(exp)
  64 Extracts 4rd word from 64-bit expression 'exp'.
  65
  66 @end table
  67
  68 They normally being used as an immediate source operand.
  69 @smallexample
  70     mov #llo(1), r10    ;       == mov  #1, r10
  71     mov #lhi(1), r10    ;       == mov  #0, r10
  72 @end smallexample
  73
  74 @node MSP430-Chars
  75 @subsection Special Characters
  76
  77 @cindex line comment character, MSP 430
  78 @cindex MSP 430 line comment character
  79 @samp{;} is the line comment character.
  80
  81 @cindex identifiers, MSP 430
  82 @cindex MSP 430 identifiers
  83 The character @samp{$} in jump instructions indicates current location and
  84 implemented only for TI syntax compatibility.
  85
  86 @node MSP430-Regs
  87 @subsection Register Names
  88
  89 @cindex MSP 430 register names
  90 @cindex register names, MSP 430
  91 General-purpose registers are represented by predefined symbols of the
  92 form @samp{r@var{N}} (for global registers), where @var{N} represents
  93 a number between @code{0} and @code{15}.  The leading
  94 letters may be in either upper or lower case; for example, @samp{r13}
  95 and @samp{R7} are both valid register names.
  96
  97 @cindex special purpose registers, MSP 430
  98 Register names @samp{PC}, @samp{SP} and @samp{SR} cannot be used as register names
  99 and will be treated as variables. Use @samp{r0}, @samp{r1}, and @samp{r2} instead.
 100
 101
 102 @node MSP430-Ext
 103 @subsection Assembler Extensions
 104 @cindex MSP430 Assembler Extensions
 105
 106 @table @code
 107
 108 @item @@rN
 109 As destination operand being treated as @samp{0(rn)}
 110
 111 @item 0(rN)
 112 As source operand being treated as @samp{@@rn}
 113
 114 @item jCOND +N
 115 Skips next N bytes followed by jump instruction and equivalent to
 116 @samp{jCOND $+N+2}
 117
 118 @end table
 119
 120 Also, there are some instructions, which cannot be found in other assemblers.
 121 These are branch instructions, which has different opcodes upon jump distance.
 122 They all got PC relative addressing mode.
 123
 124 @table @code
 125 @item   beq label
 126 A polymorph instruction which is @samp{jeq label} in case if jump distance
 127 within allowed range for cpu's jump instruction. If not, this unrolls into
 128 a sequence of
 129 @smallexample
 130   jne $+6
 131   br  label
 132 @end smallexample
 133
 134 @item bne label
 135 A polymorph instruction which is @samp{jne label} or @samp{jeq +4; br label}
 136
 137 @item blt label
 138 A polymorph instruction which is @samp{jl label} or @samp{jge +4; br label}
 139
 140 @item bltn label
 141 A polymorph instruction which is @samp{jn label} or @samp{jn +2; jmp +4; br label}
 142
 143 @item bltu label
 144 A polymorph instruction which is @samp{jlo label} or @samp{jhs +2; br label}
 145
 146 @item bge label
 147 A polymorph instruction which is @samp{jge label} or @samp{jl +4; br label}
 148
 149 @item bgeu label
 150 A polymorph instruction which is @samp{jhs label} or @samp{jlo +4; br label}
 151
 152 @item bgt label
 153 A polymorph instruction which is @samp{jeq +2; jge label} or @samp{jeq +6; jl  +4; br label}
 154
 155 @item bgtu label
 156 A polymorph instruction which is @samp{jeq +2; jhs label} or @samp{jeq +6; jlo +4; br label}
 157
 158 @item bleu label
 159 A polymorph instruction which is @samp{jeq label; jlo label} or @samp{jeq +2; jhs +4; br label}
 160
 161 @item ble label
 162 A polymorph instruction which is @samp{jeq label; jl  label} or @samp{jeq +2; jge +4; br label}
 163
 164 @item jump label
 165 A polymorph instruction which is @samp{jmp label} or @samp{br label}
 166 @end table
 167
 168
 169 @node MSP430 Floating Point
 170 @section Floating Point
 171
 172 @cindex floating point, MSP 430 (@sc{ieee})
 173 @cindex MSP 430 floating point (@sc{ieee})
 174 The MSP 430 family uses @sc{ieee} 32-bit floating-point numbers.
 175
 176 @node MSP430 Directives
 177 @section MSP 430 Machine Directives
 178
 179 @cindex machine directives, MSP 430
 180 @cindex MSP 430 machine directives
 181 @table @code
 182 @cindex @code{file} directive, MSP 430
 183 @item .file
 184 This directive is ignored; it is accepted for compatibility with other
 185 MSP 430 assemblers.
 186
 187 @quotation
 188 @emph{Warning:} in other versions of the @sc{gnu} assembler, @code{.file} is
 189 used for the directive called @code{.app-file} in the MSP 430 support.
 190 @end quotation
 191
 192 @cindex @code{line} directive, MSP 430
 193 @item .line
 194 This directive is ignored; it is accepted for compatibility with other
 195 MSP 430 assemblers.
 196
 197 @cindex @code{sect} directive, MSP 430
 198 @item .arch
 199 Currently this directive is ignored; it is accepted for compatibility with other
 200 MSP 430 assemblers.
 201
 202 @cindex @code{profiler} directive, MSP 430
 203 @item .profiler
 204 This directive instructs assembler to add new profile entry to the object file.
 205
 206 @end table
 207
 208 @node MSP430 Opcodes
 209 @section Opcodes
 210
 211 @cindex MSP 430 opcodes
 212 @cindex opcodes for MSP 430
 213 @code{@value{AS}} implements all the standard MSP 430 opcodes.  No
 214 additional pseudo-instructions are needed on this family.
 215
 216 For information on the 430 machine instruction set, see @cite{MSP430
 217 User's Manual, document slau049b}, Texas Instrument, Inc.
 218
 219 @node MSP430 Profiling Capability
 220 @section Profiling Capability
 221
 222 @cindex MSP 430 profiling capability
 223 @cindex profiling capability for MSP 430
 224 It is a performance hit to use gcc's profiling approach for this tiny target.
 225 Even more -- jtag hardware facility does not perform any profiling functions.
 226 However we've got gdb's built-in simulator where we can do anything.
 227
 228 We define new section @samp{.profiler} which holds all profiling information.
 229 We define new pseudo operation @samp{.profiler} which will instruct assembler to
 230 add new profile entry to the object file. Profile should take place at the
 231 present address.
 232
 233 Pseudo operation format:
 234
 235 @samp{.profiler flags,function_to_profile [, cycle_corrector, extra]}
 236
 237
 238 where:
 239
 240 @table @code
 241
 242 @table @code
 243
 244 @samp{flags} is a combination of the following characters:
 245
 246 @item  s
 247 function entry
 248 @item  x
 249 function exit
 250 @item  i
 251 function is in init section
 252 @item  f
 253 function is in fini section
 254 @item  l
 255 library call
 256 @item  c
 257 libc standard call
 258 @item  d
 259 stack value demand
 260 @item  I
 261 interrupt service routine
 262 @item  P
 263 prologue start
 264 @item  p
 265 prologue end
 266 @item  E
 267 epilogue start
 268 @item  e
 269 epilogue end
 270 @item  j
 271 long jump / sjlj unwind
 272 @item  a
 273 an arbitrary code fragment
 274 @item t
 275 extra parameter saved (a constant value like frame size)
 276 @end table
 277
 278 @item function_to_profile
 279 a function address
 280 @item cycle_corrector
 281 a value which should be added to the cycle counter, zero if omitted.
 282 @item extra
 283 any extra parameter, zero if omitted.
 284
 285 @end table
 286
 287 For example:
 288 @smallexample
 289 .global fxx
 290 .type fxx,@@function
 291 fxx:
 292 .LFrameOffset_fxx=0x08
 293 .profiler "scdP", fxx     ; function entry.
 294                           ; we also demand stack value to be saved
 295   push r11
 296   push r10
 297   push r9
 298   push r8
 299 .profiler "cdpt",fxx,0, .LFrameOffset_fxx  ; check stack value at this point
 300                                           ; (this is a prologue end)
 301                                           ; note, that spare var filled with
 302                                           ; the farme size
 303   mov r15,r8
 304 ...
 305 .profiler cdE,fxx         ; check stack
 306   pop r8
 307   pop r9
 308   pop r10
 309   pop r11
 310 .profiler xcde,fxx,3      ; exit adds 3 to the cycle counter
 311   ret                     ; cause 'ret' insn takes 3 cycles
 312 @end smallexample