source: xtideuniversalbios/trunk/Assembly_Library/Inc/Macros.inc@ 580

; Project name  :   Assembly Library
; Description   :   This is the place to put various generic macros.
;                   Should be included immediately after Emulate.inc
%ifndef MACROS_INC
%define MACROS_INC

;--------------------------------------------------------------------
; Skips the immediately following 2 byte instruction by using it
; as an immediate value to a dummy instruction.
; Destroys the contents of %1.
;
; SKIP2B
;   Parameters:
;       %1:     Any 16 bit general purpose register or F for flags.
;   Returns:
;       Nothing
;   Corrupts registers:
;       %1
;--------------------------------------------------------------------
%macro SKIP2B 1
    %ifidni     %1, f
        db  03Dh                    ; Opcode byte for CMP AX, <immed>
        ;db 0A9h                    ; Alt. version TEST AX, <immed>
    %elifidni   %1, ax
        db  0B8h                    ; Opcode byte for MOV AX, <immed>
    %elifidni   %1, cx
        db  0B9h                    ; Opcode byte for MOV CX, <immed>
    %elifidni   %1, dx
        db  0BAh                    ; Opcode byte for MOV DX, <immed>
    %elifidni   %1, bx
        db  0BBh                    ; Opcode byte for MOV BX, <immed>
    %elifidni   %1, sp
        db  0BCh                    ; Opcode byte for MOV SP, <immed>
    %elifidni   %1, bp
        db  0BDh                    ; Opcode byte for MOV BP, <immed>
    %elifidni   %1, si
        db  0BEh                    ; Opcode byte for MOV SI, <immed>
    %elifidni   %1, di
        db  0BFh                    ; Opcode byte for MOV DI, <immed>
    %else
        %error "Invalid parameter passed to SKIP2B"
    %endif
%endmacro


;--------------------------------------------------------------------
; Load BDA (Bios Data Area) segment to wanted segment register.
;
; Use an exclamation point (!) as the third parameter when you want
; to force the use of the register in the second parameter. This is
; useful when that register needs to be zeroed in subsequent code or
; when stack usage is undesirable (ie speed is critical).
;
; The PRESERVE_FLAGS version will zero the register with a MOV instead
; of an XOR, thus preserving the flags.  It is one byte larger on
; non-186 or higher systems.
;
; LOAD_BDA_SEGMENT_TO
; LOAD_BDA_SEGMENT_PRESERVE_FLAGS_TO
;   Parameters:
;       %1:     Destination Segment Register
;       %2:     Temporary WORD Register
;       %3:     Can be ! or empty
;   Returns:
;       %1:     BDA segment (zero)
;   Corrupts registers:
;       %2
;--------------------------------------------------------------------
%macro LOAD_BDA_SEGMENT_TO 2-3
%ifndef USE_186
    xor     %2, %2
    mov     %1, %2
%elifidn %3, !
    xor     %2, %2
    mov     %1, %2
%else
    push    BYTE 0
    pop     %1
%endif
%endmacro

%macro LOAD_BDA_SEGMENT_PRESERVE_FLAGS_TO 2-3
%ifndef USE_186
    mov     %2, 0
    mov     %1, %2
%elifidn %3, !
    mov     %2, 0
    mov     %1, %2
%else
    push    BYTE 0
    pop     %1
%endif
%endmacro


;--------------------------------------------------------------------
; eENTER_STRUCT
;   Parameters:
;       %1:     Number of bytes to reserve from stack
;   Returns:
;       SS:BP:  Ptr to beginning of struct reserved from stack
;   Corrupts registers:
;       FLAGS
;--------------------------------------------------------------------
%macro eENTER_STRUCT 1
    push    bp
    sub     sp, %1
    mov     bp, sp
%endmacro

;--------------------------------------------------------------------
; eLEAVE_STRUCT
;   Parameters:
;       %1:     Number of bytes reserved with eENTER_STRUCT
;   Returns:
;       BP:     What it was before eENTER_STRUCT
;   Corrupts registers:
;       FLAGS
;--------------------------------------------------------------------
%macro eLEAVE_STRUCT 1
    add     sp, %1
    pop     bp
%endmacro


%endif ; MACROS_INC