;File: Macro.inc
;
;basepage equates : some constants; indicating the positions
;of items of information in the program header (basepage).
;
ltpa         equ 0     ;Low TPA address
htpa         equ 4     ;High TPA address
lcode        equ 8     ;Code segment start
codelen      equ 12    ;Code segment length
ldata        equ 16    ;Data segment start
datalen      equ 20    ;Data segment length
lbss         equ 24    ;Bss segment start
bsslen       equ 28    ;Bss segment length
freelen      equ 32    ;free segment length
resvd        equ 36    ;Reserved
fcb2         equ 56    ;2nd parsed fcb
fcb1         equ 92    ;1st parsed fcb
command      equ 128   ;Command tail

;INITAPP:
;========
;Initialising a program. The program keeps a few kilobytes for the
;stack. The rest is returned to the operating system.
;The stack pointer is set to the top of the reserved memory location.
;
;Application: INITAPP
;             INITAPP stacksize
;Return status: d0 contains error status mshrink call

             .MACRO INITAPP
stack        set 32*1024                    ;32k default stacksize
             .IFNE \#  ;if different stacksize specified
stack        set \1    ;use that size instead of default
             .ENDC 
             movea.l   sp,a5                ;fetch start address basepage from stack
             movea.l   4(a5),a5
             move.l    codelen(a5),d0       ;apps size = codelength
             add.l     datalen(a5),d0       ;            +datalength
             add.l     bsslen(a5),d0        ;            +bsslength
             addi.l    #stack+256,d0        ;            +space for stack
             move.l    d0,d1                ;calculate top limit for memory block
             andi.l    #-2,d1               ;and justify to word boundary (even address)
             movea.l   d1,sp                ;SP starts at top address of stack area
             Mshrink   a5,d0                ;GEMDOS function: return unused memory
             .ENDM