mdw@git.distorted.org.uk Git - ssr/blob - StraySrc/Dynamite/dynamite/s/dynAnchor

   1 ;
   2 ; dynAnchor.s
   3 ;
   4 ; Useful handle RMA allocation for dynamite
   5 ;
   6 ; © 1994-1998 Straylight
   7 ;
   8 ;----- Licensing note -------------------------------------------------------
   9 ;
  10 ; This file is part of Straylight's Dynamite
  11 ;
  12 ; Dynamite is free software; you can redistribute it and/or modify
  13 ; it under the terms of the GNU General Public License as published by
  14 ; the Free Software Foundation; either version 2, or (at your option)
  15 ; any later version.
  16 ;
  17 ; Dynamite is distributed in the hope that it will be useful,
  18 ; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ; GNU General Public License for more details.
  21 ;
  22 ; You should have received a copy of the GNU General Public License
  23 ; along with Dynamite.  If not, write to the Free Software Foundation,
  24 ; 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25
  26
  27 ;----- Standard header ------------------------------------------------------
  28
  29                 GET     libs:header
  30                 GET     libs:swis
  31
  32 ;----- External dependencies ------------------------------------------------
  33
  34                 GET     sh.wSpace
  35
  36 ;----- Constants ------------------------------------------------------------
  37
  38 danc__chunk     EQU     16                      ;Number of handles to get
  39
  40 ;----- Main code ------------------------------------------------------------
  41
  42                 AREA    |Dynamite$$Code|,CODE,READONLY
  43
  44 ; --- danc_alloc ---
  45 ;
  46 ; On entry:     --
  47 ;
  48 ; On exit:      R0 == pointer to block allocated, or V set and pointer to
  49 ;                     error
  50 ;
  51 ; Use:          Allocates an anchor to use with dynamite from the RMA,
  52 ;               in a very quick way indeed.
  53
  54                 EXPORT  danc_alloc
  55 danc_alloc      ROUT
  56
  57                 STMFD   R13!,{R1-R3,R14}
  58
  59                 ; --- Are there any free blocks? ---
  60
  61                 LDR     R2,dyn_ancTable         ;Get the free list offset
  62                 CMP     R2,#0                   ;Are there any free blocks?
  63                 BEQ     %01danc_alloc           ;No -- better allocate some
  64
  65                 ; --- Mess about with the free list and return ---
  66
  67 00danc_alloc    LDR     R3,[R2]                 ;Get next pointer from block
  68                 STR     R3,dyn_ancTable         ;This is now first free block
  69                 MOV     R0,R2                   ;Point to the block
  70                 LDMFD   R13!,{R1-R3,PC}^        ;Restore registers and return
  71
  72                 ; --- Create a big block ---
  73
  74 01danc_alloc    MOV     R0,#6                   ;Allocate memory please
  75                 MOV     R3,#danc__chunk*4+4     ;Get the chunk size
  76                 SWI     XOS_Module              ;Allocate the big block then
  77                 LDMVSFD R13!,{R1-R3,PC}         ;If it failed, return error
  78
  79                 LDR     R14,dyn_ancList         ;Load current list head
  80                 STR     R2,dyn_ancList          ;Save this as new list head
  81                 STR     R14,[R2],#4             ;And save old list head
  82
  83                 ; --- Now set up the links for the free list ---
  84
  85                 MOV     R0,#0                   ;Next free pointer start at 0
  86                 SUB     R3,R3,#8                ;Offset to next field of sub
  87 02danc_alloc    STR     R0,[R2,R3]              ;Store in next field
  88                 ADD     R0,R2,R3                ;Point to that block
  89                 SUBS    R3,R3,#4                ;Point to previous block
  90                 BGE     %02danc_alloc           ;If more to do, continue...
  91
  92                 ; --- The links are set up -- now take off a block ---
  93
  94                 B       %00danc_alloc           ;Then allocate as normal
  95
  96                 LTORG
  97
  98 ; --- danc_free ---
  99 ;
 100 ; On entry:     R0 == pointer to block
 101 ;
 102 ; On exit:      Registers preserved
 103 ;
 104 ; Use:          Frees an anchor allocated using danc_alloc.
 105
 106                 EXPORT  danc_free
 107 danc_free       ROUT
 108
 109                 STMFD   R13!,{R0,R1,R14}        ;Preserve registers
 110
 111                 ; --- Mess about with the list ---
 112
 113                 LDR     R1,dyn_ancTable         ;Get current first block
 114                 STR     R1,[R0]                 ;Store in newly freed block
 115                 STR     R0,dyn_ancTable         ;And insert new block in list
 116                 LDMFD   R13!,{R0,R1,PC}^        ;Oh, and return to caller
 117
 118                 LTORG
 119
 120 ; --- danc_quit ---
 121 ;
 122 ; On entry:     --
 123 ;
 124 ; On exit:      --
 125 ;
 126 ; Use:          Frees everyone's anchors nicely when the module quits.
 127
 128                 EXPORT  danc_quit
 129 danc_quit       ROUT
 130
 131                 STMFD   R13!,{R0-R2,R14}        ;Save some registers
 132                 LDR     R2,dyn_ancList          ;Load the list head
 133                 CMP     R2,#0                   ;Is there anything to do?
 134                 LDMEQFD R13!,{R0-R2,PC}^        ;No -- return then
 135                 MOV     R0,#7                   ;Free RMA block
 136 00danc_quit     LDR     R1,[R2,#0]              ;Load the next pointer
 137                 SWI     XOS_Module              ;Free the block
 138                 MOVS    R2,R1                   ;Point to next one
 139                 BNE     %00danc_quit            ;And loop round for more
 140                 LDMFD   R13!,{R0-R2,PC}^        ;Return when all done
 141
 142                 LTORG
 143
 144 ;----- That's all, folks ----------------------------------------------------
 145
 146                 END