mdw@git.distorted.org.uk Git - ssr/blob - StraySrc/Libraries/Core/sh/flex

   1 ;
   2 ; flex.sh
   3 ;
   4 ; Flexible memory handling
   5 ;
   6 ; © 1994-1998 Straylight
   7 ;
   8
   9 ;----- Licensing note -------------------------------------------------------
  10 ;
  11 ; This file is part of Straylight's Flex.
  12 ;
  13 ; Flex is free software; you can redistribute it and/or modify
  14 ; it under the terms of the GNU General Public License as published by
  15 ; the Free Software Foundation; either version 2, or (at your option)
  16 ; any later version.
  17 ;
  18 ; Flex is distributed in the hope that it will be useful,
  19 ; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ; GNU General Public License for more details.
  22 ;
  23 ; You should have received a copy of the GNU General Public License
  24 ; along with Flex.  If not, write to the Free Software Foundation,
  25 ; 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  26
  27 ;----- Overview -------------------------------------------------------------
  28 ;
  29 ; Functions provided:
  30 ;
  31 ;  flex_reduce
  32 ;  flex_compact
  33 ;  flex_free
  34 ;  flex_alloc
  35 ;  flex_size
  36 ;  flex_extend
  37 ;  flex_midExtend
  38 ;  flex_init
  39 ;  flex_save
  40 ;  flex_load
  41 ;  flex_dump
  42 ;
  43 ; Macros provided:
  44 ;
  45 ;   FSAVE
  46 ;   FLOAD
  47
  48 ;+              LIB     sapphire:^.bsh.flex
  49
  50 ; --- flex_reduce ---
  51 ;
  52 ; On entry:     --
  53 ;
  54 ; On exit:      --
  55 ;
  56 ; Use:          Compacts the flex heap by one iteration.
  57
  58                 IMPORT  flex_reduce
  59
  60 ; --- flex_compact ---
  61 ;
  62 ; On entry:     --
  63 ;
  64 ; On exit:      --
  65 ;
  66 ; Use:          Completely compacts the flex heap.
  67
  68                 IMPORT  flex_compact
  69
  70 ; --- flex_free ---
  71 ;
  72 ; On entry:     R0 == pointer to the flex anchor
  73 ;
  74 ; On exit:      --
  75 ;
  76 ; Use:          Frees a flex block allocated by flex_alloc.
  77
  78                 IMPORT  flex_free
  79
  80 ; --- flex_alloc ---
  81 ;
  82 ; On entry:     R0 == pointer to a flex anchor
  83 ;               R1 == desired size of flex block
  84 ;
  85 ; On exit:      CS if no memory could be allocated, CC otherwise
  86 ;
  87 ; Use:          Allocates a block in the shifting heap.
  88
  89                 IMPORT  flex_alloc
  90
  91 ; --- flex_size ---
  92 ;
  93 ; On entry:     R0 == pointer to flex anchor
  94 ;
  95 ; On exit:      R0 == size of allocated block
  96 ;
  97 ; Use:          Reads the size of a flex block.
  98
  99                 IMPORT  flex_size
 100
 101 ; --- flex_extend ---
 102 ;
 103 ; On entry:     R0 == pointer to flex anchor
 104 ;               R1 == new size of block to set
 105 ;
 106 ; On exit:      CS if it failed due to lack of memory, CC otherwise
 107 ;
 108 ; Use:          Alters the size of a block to the given value.
 109
 110                 IMPORT  flex_extend
 111
 112 ; --- flex_midExtend ---
 113 ;
 114 ; On entry:     R0 == pointer to a flex anchor
 115 ;               R1 == `at' -- position in block to extend from
 116 ;               R2 == `by' -- how many bytes to extend (may be -ve)
 117 ;
 118 ; On exit:      CS if it failed due to lack of memory, CC otherwise
 119 ;
 120 ; Use:          Either creates a gap in a block (by>0) or deletes bytes
 121 ;               from a block.  This is always done in such a way that the
 122 ;               byte originally at offset `at' is now at offset `at'+`by'.
 123
 124                 IMPORT  flex_midExtend
 125
 126 ; --- flex_init ---
 127 ;
 128 ; On entry:     --
 129 ;
 130 ; On exit:      --
 131 ;
 132 ; Use:          Initialises the flex heap for use.
 133
 134                 IMPORT  flex_init
 135
 136 ; --- flex_save ---
 137 ;
 138 ; On entry:     --
 139 ;
 140 ; On exit:      --
 141 ;
 142 ; Use:          Saves some registers on the flex relocation stack.  R13
 143 ;               and R14 cannot be saved -- these registers are corrupted
 144 ;               during this routine's execution.
 145 ;
 146 ;               Values saved on the flex relocation stack are adjusted as
 147 ;               flex moves blocks of memory around, so that they still point
 148 ;               to the same thing as they did before.  Obviously, values
 149 ;               which aren't pointers into flex blocks may be corrupted.
 150 ;               Values pointing to objects deleted (either free blocks, or
 151 ;               areas removed by flex_midExtend) may also be corrupted.
 152 ;
 153 ;               Since this routine takes no arguments, some other method has
 154 ;               to be used.  The method chosen is to follow the call to
 155 ;               flex_save with a LDM or STM instruction containing the
 156 ;               registers to be saved.  This instruction is skipped by the
 157 ;               routine, and thus not executed.
 158 ;
 159 ;               Note that if you give the LDM or STM the same condition code
 160 ;               as the BL preceding it, it will never be executed, since
 161 ;               flex_save skips it if the condition is true and it can't be
 162 ;               executed if the condition is false.
 163
 164                 [       :DEF:FLEX_STACK
 165                 IMPORT  flex_save
 166                 ]
 167
 168 ; --- flex_load ---
 169 ;
 170 ; On entry:     --
 171 ;
 172 ; On exit:      Registers loaded from relocation stack as requested
 173 ;
 174 ; Use:          Restores registers saved on flex's relocation stack.  See
 175 ;               flex_save for calling information and details about the
 176 ;               relocation stack.
 177
 178                 [       :DEF:FLEX_STACK
 179                 IMPORT  flex_load
 180                 ]
 181
 182 ;----- Useful macros --------------------------------------------------------
 183
 184 ; --- Macro: FSAVE ---
 185 ;
 186 ; Arguments:    rList == quoted register list to save on relocation stack
 187 ;
 188 ; Use:          Assembles code to write the given register list on the
 189 ;               flex relocation stack.  The register list should be in the
 190 ;               same form as that for an STM or LDM instruction.
 191 ;
 192 ;               For full details about the flex relocation stack, see
 193 ;               flex_save.
 194
 195                 [       :DEF:FLEX_STACK
 196
 197                 MACRO
 198 $label          FSAVE   $rList
 199
 200                 BL      flex_save
 201                 STMEA   R14!,{$rList}
 202
 203                 MEND
 204
 205                 ]
 206
 207 ; --- Macro: FLOAD ---
 208 ;
 209 ; Arguments:    rList == quoted register list to read from relocation stack
 210 ;
 211 ; Use:          Assembles code to read the given register list from the
 212 ;               flex relocation stack.  The register list should be in the
 213 ;               same form as that for an STM or LDM instruction.
 214 ;
 215 ;               For full details about the flex relocation stack, see
 216 ;               flex_save.
 217
 218                 [       :DEF:FLEX_STACK
 219
 220                 MACRO
 221 $label          FLOAD   $rList
 222
 223                 BL      flex_load
 224                 LDMEA   R14!,{$rList}
 225
 226                 MEND
 227
 228                 ]
 229
 230 ;----- That's all, folks ----------------------------------------------------
 231
 232                 END