mdw@git.distorted.org.uk Git - ssr/blob - StraySrc/Libraries/Sapphire/s/mem

   1 ;
   2 ; mem.s
   3 ;
   4 ; Operations on memory blocks (TMA)
   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 ;----- Standard header ------------------------------------------------------
  28
  29                 GET     libs:swis
  30                 GET     libs:header
  31
  32 ;----- External dependencies ------------------------------------------------
  33 ;
  34 ; None.
  35
  36 ;----- Main code ------------------------------------------------------------
  37
  38                 AREA    |Sapphire$$Code|,CODE,READONLY
  39
  40 ; --- mem_set ---
  41 ;
  42 ; On entry:     R0 == pointer to a block of memory (word-aligned)
  43 ;               R1 == size of the block
  44 ;               R2 == word value to store in the block
  45 ;
  46 ; On exit:      --
  47 ;
  48 ; Use:          Initialises a block by filling every word within it with the
  49 ;               same value.  This is normally 0, although maybe MOVS PC,#0
  50 ;               might be useful too.
  51
  52                 EXPORT  mem_set
  53 mem_set         ROUT
  54
  55                 STMFD   R13!,{R0-R8,R14}        ;Stack registers away
  56
  57                 ; --- Set up seed value in lots of registers ---
  58
  59                 MOV     R3,R2
  60                 MOV     R4,R2
  61                 MOV     R5,R2
  62                 MOV     R6,R2
  63                 MOV     R7,R2
  64                 MOV     R8,R2
  65                 MOV     R14,R2
  66
  67                 ; --- Do the copy ---
  68
  69 00mem_set       SUBS    R1,R1,#32               ;Is there enough for fastblat
  70                 STMGEIA R0!,{R2-R8,R14}         ;Yes -- *blat*
  71                 BGE     %00mem_set
  72
  73                 ; --- Now to word blats ---
  74
  75                 ADD     R1,R1,#32               ;How much left to do?
  76 01mem_set       SUBS    R1,R1,#4                ;Enough for a word?
  77                 STRGE   R14,[R0],#4             ;Yes -- store it
  78                 BGE     %01mem_set              ;And go round again
  79
  80                 LDMFD   R13!,{R0-R8,PC}^        ;Return to caller
  81
  82                 LTORG
  83
  84 ;----- That's all folks -----------------------------------------------------
  85
  86                 END