mdw@git.distorted.org.uk Git - ssr/blob - StraySrc/Libraries/Sapphire/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 Sapphire library.
  12 ;
  13 ; Sapphire 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 ; Sapphire 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 Sapphire.  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_stackPtr
  40 ;  flex_save
  41 ;  flex_load
  42 ;  flex_dump
  43 ;
  44 ; Macros provided:
  45 ;
  46 ;   FSAVE
  47 ;   FLOAD
  48
  49                 [       :LNOT::DEF:flex__dfn
  50                 GBLL    flex__dfn
  51
  52 ;+              LIB     sapphire:^.bsh.flex
  53
  54 ; --- flex_reduce ---
  55 ;
  56 ; On entry:     --
  57 ;
  58 ; On exit:      --
  59 ;
  60 ; Use:          Compacts the flex heap by one iteration.
  61
  62                 IMPORT  flex_reduce
  63
  64 ; --- flex_compact ---
  65 ;
  66 ; On entry:     --
  67 ;
  68 ; On exit:      --
  69 ;
  70 ; Use:          Completely compacts the flex heap.
  71
  72                 IMPORT  flex_compact
  73
  74 ; --- flex_free ---
  75 ;
  76 ; On entry:     R0 == pointer to the flex anchor
  77 ;
  78 ; On exit:      --
  79 ;
  80 ; Use:          Frees a flex block allocated by flex_alloc.
  81
  82                 IMPORT  flex_free
  83
  84 ; --- flex_alloc ---
  85 ;
  86 ; On entry:     R0 == pointer to a flex anchor
  87 ;               R1 == desired size of flex block
  88 ;
  89 ; On exit:      CS if no memory could be allocated, CC otherwise
  90 ;
  91 ; Use:          Allocates a block in the shifting heap.
  92
  93                 IMPORT  flex_alloc
  94
  95 ; --- flex_size ---
  96 ;
  97 ; On entry:     R0 == pointer to flex anchor
  98 ;
  99 ; On exit:      R0 == size of allocated block
 100 ;
 101 ; Use:          Reads the size of a flex block.
 102
 103                 IMPORT  flex_size
 104
 105 ; --- flex_extend ---
 106 ;
 107 ; On entry:     R0 == pointer to flex anchor
 108 ;               R1 == new size of block to set
 109 ;
 110 ; On exit:      CS if it failed due to lack of memory, CC otherwise
 111 ;
 112 ; Use:          Alters the size of a block to the given value.
 113
 114                 IMPORT  flex_extend
 115
 116 ; --- flex_midExtend ---
 117 ;
 118 ; On entry:     R0 == pointer to a flex anchor
 119 ;               R1 == `at' -- position in block to extend from
 120 ;               R2 == `by' -- how many bytes to extend (may be -ve)
 121 ;
 122 ; On exit:      CS if it failed due to lack of memory, CC otherwise
 123 ;
 124 ; Use:          Either creates a gap in a block (by>0) or deletes bytes
 125 ;               from a block.  This is always done in such a way that the
 126 ;               byte originally at offset `at' is now at offset `at'+`by'.
 127
 128                 IMPORT  flex_midExtend
 129
 130 ; --- flex_init ---
 131 ;
 132 ; On entry:     --
 133 ;
 134 ; On exit:      --
 135 ;
 136 ; Use:          Initialises the flex heap for use.
 137
 138                 IMPORT  flex_init
 139
 140 ; --- flex_stackPtr ---
 141 ;
 142 ; On entry:     R0 == 0 to read, or value to set
 143 ;
 144 ; On exit:      R0 == old value
 145 ;
 146 ; Use:          Either reads or writes the flex stack pointer.  This sort
 147 ;               of thing is useful in exception handlers etc.
 148
 149                 IMPORT  flex_stackPtr
 150
 151 ; --- flex_save ---
 152 ;
 153 ; On entry:     --
 154 ;
 155 ; On exit:      --
 156 ;
 157 ; Use:          Saves some registers on the flex relocation stack.  R13
 158 ;               and R14 cannot be saved -- these registers are corrupted
 159 ;               during this routine's execution.
 160 ;
 161 ;               Values saved on the flex relocation stack are adjusted as
 162 ;               flex moves blocks of memory around, so that they still point
 163 ;               to the same thing as they did before.  Obviously, values
 164 ;               which aren't pointers into flex blocks may be corrupted.
 165 ;               Values pointing to objects deleted (either free blocks, or
 166 ;               areas removed by flex_midExtend) may also be corrupted.
 167 ;
 168 ;               Since this routine takes no arguments, some other method has
 169 ;               to be used.  The method chosen is to follow the call to
 170 ;               flex_save with a LDM or STM instruction containing the
 171 ;               registers to be saved.  This instruction is skipped by the
 172 ;               routine, and thus not executed.
 173 ;
 174 ;               Note that if you give the LDM or STM the same condition code
 175 ;               as the BL preceding it, it will never be executed, since
 176 ;               flex_save skips it if the condition is true and it can't be
 177 ;               executed if the condition is false.
 178
 179                 IMPORT  flex_save
 180
 181 ; --- flex_load ---
 182 ;
 183 ; On entry:     --
 184 ;
 185 ; On exit:      Registers loaded from relocation stack as requested
 186 ;
 187 ; Use:          Restores registers saved on flex's relocation stack.  See
 188 ;               flex_save for calling information and details about the
 189 ;               relocation stack.
 190
 191                 IMPORT  flex_load
 192
 193 ;----- Useful macros --------------------------------------------------------
 194
 195 ; --- Macro: FSAVE ---
 196 ;
 197 ; Arguments:    rList == quoted register list to save on relocation stack
 198 ;
 199 ; Use:          Assembles code to write the given register list on the
 200 ;               flex relocation stack.  The register list should be in the
 201 ;               same form as that for an STM or LDM instruction.
 202 ;
 203 ;               For full details about the flex relocation stack, see
 204 ;               flex_save.
 205
 206                 MACRO
 207 $label          FSAVE   $rList
 208 $label
 209                 BL      flex_save
 210                 STMEA   R14!,{$rList}
 211
 212                 MEND
 213
 214 ; --- Macro: FLOAD ---
 215 ;
 216 ; Arguments:    rList == quoted register list to read from relocation stack
 217 ;
 218 ; Use:          Assembles code to read the given register list from the
 219 ;               flex relocation stack.  The register list should be in the
 220 ;               same form as that for an STM or LDM instruction.
 221 ;
 222 ;               For full details about the flex relocation stack, see
 223 ;               flex_save.
 224
 225                 MACRO
 226 $label          FLOAD   $rList
 227 $label
 228                 BL      flex_load
 229                 LDMEA   R14!,{$rList}
 230
 231                 MEND
 232
 233                 ]
 234
 235 ;----- That's all, folks ----------------------------------------------------
 236
 237                 END