gas/doc/c-pru.texi

   1 @c Copyright (C) 2015-2022 Free Software Foundation, Inc.
   2 @c This is part of the GAS manual.
   3 @c For copying conditions, see the file as.texinfo.
   4 @c man end
   5 @ifset GENERIC
   6 @page
   7 @node PRU-Dependent
   8 @chapter PRU Dependent Features
   9 @end ifset
  10
  11 @cindex PRU support
  12 @menu
  13 * PRU Options::              Options
  14 * PRU Syntax::               Syntax
  15 * PRU Relocations::          Relocations
  16 * PRU Directives::           PRU Machine Directives
  17 * PRU Opcodes::              Opcodes
  18 @end menu
  19
  20 @node PRU Options
  21 @section Options
  22 @cindex PRU options
  23 @cindex options for PRU
  24
  25 @c man begin OPTIONS
  26 @table @gcctabopt
  27
  28 @cindex @code{mlink-relax} command-line option, PRU
  29 @item -mlink-relax
  30 Assume that LD would optimize LDI32 instructions by checking the upper
  31 16 bits of the @var{expression}. If they are all zeros, then LD would
  32 shorten the LDI32 instruction to a single LDI. In such case @code{@value{AS}}
  33 will output DIFF relocations for diff expressions.
  34
  35 @cindex @code{mno-link-relax} command-line option, PRU
  36 @item -mno-link-relax
  37 Assume that LD would not optimize LDI32 instructions. As a consequence,
  38 DIFF relocations will not be emitted.
  39
  40 @cindex @code{mno-warn-regname-label} command-line option, PRU
  41 @item -mno-warn-regname-label
  42 Do not warn if a label name matches a register name. Usually assembler
  43 programmers will want this warning to be emitted. C compilers may want
  44 to turn this off.
  45
  46 @end table
  47 @c man end
  48
  49 @node PRU Syntax
  50 @section Syntax
  51 @menu
  52 * PRU Chars::                Special Characters
  53 @end menu
  54
  55
  56 @node PRU Chars
  57 @subsection Special Characters
  58
  59 @cindex line comment character, PRU
  60 @cindex PRU line comment character
  61 @samp{#} and @samp{;} are the line comment characters.
  62
  63
  64 @node PRU Relocations
  65 @section PRU Machine Relocations
  66
  67 @cindex machine relocations, PRU
  68 @cindex PRU machine relocations
  69
  70 @table @code
  71
  72 @cindex @code{pmem} directive, PRU
  73 @item %pmem(@var{expression})
  74 Convert @var{expression} from byte-address to a
  75 word-address.  In other words, shift right by two.
  76
  77 @item %label(@var{expression})
  78 Mark the given operand as a label. This is useful if you need to jump to
  79 a label that matches a register name.
  80
  81 @smallexample
  82 @group
  83 r1:
  84     jmp r1              ; Will jump to register R1
  85     jmp %label(r1)      ; Will jump to label r1
  86 @end group
  87 @end smallexample
  88
  89 @end table
  90
  91
  92 @node PRU Directives
  93 @section PRU Machine Directives
  94
  95 @cindex machine directives, PRU
  96 @cindex PRU machine directives
  97
  98 @table @code
  99
 100 @cindex @code{align} directive, PRU
 101 @item .align @var{expression} [, @var{expression}]
 102 This is the generic @code{.align} directive, however
 103 this aligns to a power of two.
 104
 105 @cindex @code{word} directive, PRU
 106 @item .word @var{expression}
 107 Create an aligned constant 4 bytes in size.
 108
 109 @cindex @code{dword} directive, PRU
 110 @item .dword @var{expression}
 111 Create an aligned constant 8 bytes in size.
 112
 113 @cindex @code{2byte} directive, PRU
 114 @item .2byte @var{expression}
 115 Create an unaligned constant 2 bytes in size.
 116
 117 @cindex @code{4byte} directive, PRU
 118 @item .4byte @var{expression}
 119 Create an unaligned constant 4 bytes in size.
 120
 121 @cindex @code{8byte} directive, PRU
 122 @item .8byte @var{expression}
 123 Create an unaligned constant 8 bytes in size.
 124
 125 @cindex @code{16byte} directive, PRU
 126 @item .16byte @var{expression}
 127 Create an unaligned constant 16 bytes in size.
 128
 129 @cindex @code{set no_warn_regname_label} directive, PRU
 130 @item .set no_warn_regname_label
 131 Do not output warnings when a label name matches a register name. Equivalent
 132 to passing the @code{-mno-warn-regname-label} command-line option.
 133
 134 @end table
 135
 136 @node PRU Opcodes
 137 @section Opcodes
 138
 139 @cindex PRU opcodes
 140 @cindex opcodes for PRU
 141 @code{@value{AS}} implements all the standard PRU core V3 opcodes in the
 142 original pasm assembler.  Older cores are not supported by @code{@value{AS}}.
 143
 144 GAS also implements the LDI32 pseudo instruction for loading a 32-bit
 145 immediate value into a register.
 146
 147 @smallexample
 148        ldi32   sp, __stack_top
 149        ldi32   r14, 0x12345678
 150 @end smallexample