2021-01-21 23:28:57 +01:00
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; Program segment prefix headers and constants
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section .bss
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curpsp: resw 1
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absolute 0
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resb 2 ; ret 0 exit
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resb 2 ; next unusable segment
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PSPDD: resb 1 ; BYTE default drive
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; CP/M entry point
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resb 1 ; instruction byte
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resw 1 ; usable length of segment (needs to be here for compata)
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resb 4 ; opcodes to call us
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; saved userdata
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PSPAX: resw 1
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PSPCX: resw 1
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; SS:SP
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PSPSP: resw 1
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PSPSS: resw 1
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; DS:DX
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PSPDX: resw 1
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PSPDS: resw 1
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; ES:BX
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PSPBX: resw 1
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PSPES: resw 1
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PSPDTA: resd 1 ; DWORD ptr to disk transfer area
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section .text
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; set default drive for current process
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; IN dl drive number
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setdd: push es
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mov es, [curpsp]
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mov [es:PSPDD], dl
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pop es
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ret
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; get default drive for current process
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; OUT al drive number
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getdd: push es
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mov es, [curpsp]
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mov al, [es:PSPDD]
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pop es
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ret
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; set DTA ptr
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; IN es:bx far ptr
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2021-01-21 23:30:35 +01:00
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setdta: push ds
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2021-01-21 23:28:57 +01:00
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mov ds, [curpsp]
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mov [PSPDTA], bx
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mov [PSPDTA+2], es
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2021-01-21 23:30:35 +01:00
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pop ds
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2021-01-21 23:28:57 +01:00
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; get DTA ptr
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; OUT es:bx far ptr
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getdta: mov es, [curpsp]
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les bx, [es:PSPDTA]
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ret
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