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view level1/modules/kernel/fssvc.asm @ 3246:be3446f758ca

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Updated dwread.asm and dwwrite.asm so that the 6551 routines could have specially defined flags so that some of the addresses could be overridden by the make files if needed.
author David Ladd <drencor-xeen@users.sourceforge.net>
date Sun, 11 Mar 2018 01:30:30 -0600
parents f273e28ea8d0
children
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FSSvc    ldy   R$Y,u                   get caller's Y
         bra   InstSSvc                install the service
SSvcLoop tfr   b,a                     put syscall code in A
         anda  #$7F                    kill hi bit
         cmpa  #$7F                    is code $7F?
         beq   SSvcOK
         cmpa  #$37                    compare against highest call allowed
         bcs   SSvcOK                  branch if A less than highest call
         comb
         ldb   #E$ISWI
         rts
SSvcOK   lslb
         ldu   <D.SysDis
         leau  b,u                     U points to entry in table
         ldd   ,y++                    get addr of func
         leax  d,y                     get absolute addr
         stx   ,u                      store in system table
         bcs   InstSSvc                branch if system only
         stx   <$70,u                  else store in user table too
InstSSvc ldb   ,y+                     get system call code in B
         cmpb  #$80                    end of table?
         bne   SSvcLoop                branch if not
         rts