TITLE DRIVSUBS.ASM - Module for reading driver statistics table.
SUBTITLE Code Segment Symbolic Definitions.
;****************************************************************************
; The following segment declaration is to allow interaction with the
; Microsoft 4.0 C-compiler:
;****************************************************************************
_TEXT   segment byte public 'CODE'
        .286    ;Enables assembly of nonpriveleged 80286 instructions.
        SUBTITLE C-language subroutine "_GetByte"
        PAGE
;****************************************************************************
; Subroutine "_GetByte": reads one byte from a given segment and offset;
; Assumes:
; C-language near calling sequence is: GetByte(segment, offset);
; (note the absence of the underscore prefix character required for linker)
; Returns:
; ax = returned byte, sign-extended;
;****************************************************************************
;
public  _GetByte
_GetByte proc    near
;
        push    bp              ;save caller's frame pointer on stack
        mov     bp, sp          ;frame pointer points to old sp
        push    ds              ;save caller's ds on stack
        push    bx              ;save caller's bx on stack
        mov     ds, [bp+4]      ;ds = entry segment value
        mov     bx, [bp+6]      ;bx = entry offset value
        mov     al, [bx]        ;al = byte at segment:offset
        cbw                     ;sign-extend al into ax
        pop     bx              ;restore caller's bx from stack
        pop     ds              ;restore caller's ds from stack
        mov     sp, bp          ;remove local variable space if any
        pop     bp              ;restore caller's frame pointer from stack
        ret                     ;near return to our caller
;
;****************************************************************************
; End of subroutine "_GetByte"...    TVJM.
;****************************************************************************
_GetByte        endp
        SUBTITLE C-language subroutine "_GetWord"
        PAGE
;****************************************************************************
; Subroutine "_GetWord": reads one word from a given segment and offset;
; Assumes:
; C-language near calling sequence is: GetWord(segment, offset);
; (note the absence of the underscore prefix character required for linker)
; Returns:
; ax = returned word;
;****************************************************************************
;
public  _GetWord
_GetWord proc    near
;
        push    bp              ;save caller's frame pointer on stack
        mov     bp, sp          ;frame pointer points to old sp
        push    ds              ;save caller's ds on stack
        push    bx              ;save caller's bx on stack
        mov     ds, [bp+4]      ;ds = entry segment value
        mov     bx, [bp+6]      ;bx = entry offset value
        mov     ax, [bx]        ;ax = word at segment:offset
        pop     bx              ;restore caller's bx from stack
        pop     ds              ;restore caller's ds from stack
        mov     sp, bp          ;remove local variable space if any
        pop     bp              ;restore caller's frame pointer from stack
        ret                     ;near return to our caller
;
;****************************************************************************
; End of subroutine "_GetWord"...    TVJM.
;****************************************************************************
_GetWord        endp
        SUBTITLE C-language subroutine "_GetLong"
        PAGE
;****************************************************************************
; Subroutine "_GetLong": reads one longword from a given segment and offset;
; Assumes:
; C-language near calling sequence is: GetLong(segment, offset);
; (note the absence of the underscore prefix character required for linker)
; Returns:
; ax = lo-order word, dx = hi-order word
;****************************************************************************
;
public  _GetLong
_GetLong proc    near
;
        push    bp              ;save caller's frame pointer on stack
        mov     bp, sp          ;frame pointer points to old sp
        push    ds              ;save caller's ds on stack
        push    bx              ;save caller's bx on stack
        mov     ds, [bp+4]      ;ds = entry segment value
        mov     bx, [bp+6]      ;bx = entry offset value
        mov     ax, [bx+0]      ;ax = lo-word at segment:offset
        mov     dx, [bx+2]      ;dx = hi-word at segment:offset
        pop     bx              ;restore caller's bx from stack
        pop     ds              ;restore caller's ds from stack
        mov     sp, bp          ;remove local variable space if any
        pop     bp              ;restore caller's frame pointer from stack
        ret                     ;near return to our caller
;
;****************************************************************************
; End of subroutine "_GetLong"...    TVJM.
;****************************************************************************
_GetLong        endp
_TEXT           ends
                end