?? rxdosexe.asm
字號:
getarg ax, _requiredParas
getarg dx, _maxRequestedParas
call _allocateMinMaxMemBlock ; return seg pointer to avail memory
jc _loaderAllocMemory_50 ; if insufficient space to load -->
storarg _programPSP, es ; save PSP seg address
storarg _allocatedSize, cx ; allocated size
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; create child PSP
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
getdarg dx, ax, _ExecBlock ; load exec structure
call createPSP ; build PSP (cx contains alloc size)
storarg _StartSegment, es ; PSP here
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; set Env Block in PSP
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
getarg es, _programPSP
getarg ax, _AllocEnv ; alloc environment
mov word ptr es:[ pspEnvironment ], ax ; environment block
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; insure parent's handle are set for both blocks
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
mov dx, es ; PSP address
mov ax, es
sub ax, (sizeMEMBLOCK/ PARAGRAPH)
mov es, ax ; point to allocation block
mov word ptr es:[ _memParent ], dx ; assign parent
getarg ax, _AllocEnv
or ax, ax ; none required ?
jz _loaderAllocMemory_56 ; no -->
sub ax, (sizeMEMBLOCK/ PARAGRAPH)
mov es, ax ; point to allocation block
mov word ptr es:[ _memParent ], dx ; assign parent
jmp short _loaderAllocMemory_56 ; if everything is ok -->
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; free env block if error
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
_loaderAllocMemory_50:
getarg ax, _AllocEnv
or ax, ax ; Env allocated ?
jz _loaderAllocMemory_54 ; no -->
mov es, ax
call _freeMemBlock
_loaderAllocMemory_54:
SetError pexterrNotEnoughMemory, _loaderAllocMemory_56
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; return
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
_loaderAllocMemory_56:
getarg ax, _programPSP
getarg es, _StartSegment
getarg cx, _allocatedSize
_loaderAllocMemory_66:
Return
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Compute Checksum ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Input: ;
; es:di start address of block ;
; cx number of bytes in block ;
; ;
; Output: ;
; ax sum, ignoring carry, of all words in block ;
;...............................................................;
computeChecksum:
push di
push cx
shr cx, 1
xor ax, ax
computeChecksum_04:
add ax, word ptr es:[ di ]
add di, 2
loop computeChecksum_04
pop cx
pop di
ret
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Set Execution State ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Usage: ;
; ds:dx address of SETEXEC block ;
; ;
;...............................................................;
_SetExecuteMode:
clc
ret
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Append Program Name to Environment Block ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Usage: ;
; es environment block ;
; ds:dx program name ;
; ;
;...............................................................;
appendProgramNametoEnv:
mov si, dx ; save name to program
xor al, al ; byte to search for
xor di, di ; byte offset
mov cx, 0FFFFh ; maximum length
appendPgmName_10:
repnz scasb ; scan for end of string
scasb ; test if double null
jne appendPgmName_10 ;
mov ax, 0001 ; # strings to append
stosw ;
appendPgmName_14:
lodsb
stosb
or al, al ; null byte copied ?
jnz appendPgmName_14 ; not yet -->
ret
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Get Size of Envirnment String ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Input: ;
; es environment block string (must be non-zero) ;
; ;
; Output: ;
; cx # paragraphs requested. (if zero, allocate none). ;
; ;
;...............................................................;
_getSizeOfEnvString:
push di
xor al, al ; byte to search for
xor di, di ; byte offset
mov cx, 0FFFFh ; maximum length
getSizeEnv_10:
repnz scasb ; scan for end of string
scasb ; test if double null
jne getSizeEnv_10 ;
mov cx, di ; get length
add cx, (sizeEXPANDNAME + sizeParagraph - 1)/2 ; include size of trailing filename
add cx, 2 ; include count word
shr cx, 1 ; size to paragraphs
shr cx, 1
shr cx, 1
shr cx, 1
or cx, cx
pop di
ret
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Set Program Name in Memory Block ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Input: ;
; es block to change (not header address) ;
; dx full or partial filename (null terminated) ;
; ;
;...............................................................;
_setProgramNameInMemBlock:
SaveSegments
mov ax, es
or ax, ax ; no destination mem block ?
jz _setProgName_22 ; ignore set name -->
sub ax, (sizeMEMBLOCK/ PARAGRAPH)
push ax ; save seg address
mov ax, ss
mov ds, ax ; just in case it's not
mov es, ax ; scan expanded name
xor ax, ax
mov cx, -1
mov di, dx ; scan name for null terminator
repnz scasb ; scan name
not cx ; valid count
_setProgName_08:
cmp byte ptr es:[ di - 1 ], '\'
jz _setProgName_12 ; we have start of name -->
dec di
loop _setProgName_08
mov di, dx ; name contained no path
_setProgName_12:
mov si, di ; save filename
mov dx, di ; save filename
pop es ; restore memblock seg address
mov ax, 2020h
mov di, offset _memPgmName ; where to init
mov cx, sizefnName / 2 ; size filename in words
rep stosw ; initialize to blanks
mov di, offset _memPgmName ; where to init
mov cx, sizefnName ; size filename in bytes
_setProgName_16:
lodsb ; get byte
or al, al ; end of name ?
jz _setProgName_22 ; if end of name -->
cmp al, '.' ; extension ?
jz _setProgName_22 ; if end of name -->
stosb ; save character in mem block
loop _setProgName_16
_setProgName_22:
RestoreSegments
ret
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; If Overlay Loader, return size ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Input: ;
; al mode flag ;
; cx:dx file size to return ;
; ;
;...............................................................;
ifOverlayLoader:
push es
push si
RetCallersStackFrame es, si ; save size only if non-Overlay
mov word ptr es:[ _CX ][ si ], dx
mov word ptr es:[ _BX ][ si ], cx
mov word ptr es:[ _AX ][ si ], 0000
pop si
pop es
cmp al, execLoadOverlay ; load overlay ?
clc
ret
RxDOS ENDS
END
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