我们先看看如何在汇编语言内部处理__fastcall函数. 假设我们要用汇编定义并调用这样一个函数:
int __fastcall AddNum(int x, int y, int z) {
return x + y + z;
}
如何定义这个函数? 容易看出有3个参数, 根据__fastcall调用的特点, x应当存入ecx寄存器中, y则进edx, 还有一个参数z则采用堆栈传递, 函数执行完毕应当自己清理压入的参数(retn 4返回), 不难得到我们的初始想法如下:
AddNum PROC z ;这里x, y不见了,因为它们都跑寄存器里去了
mov eax, ecx ;ecx即为x参数
add eax, edx ;edx即为y参数, 这儿计算x + y
add eax, z ;最后加上z, 此时eax中为返回值x + y + z
retn 4 ;自己清除z参数
AddNum ENDP
IFB <arg>
ret num
ELSE
IF @SizeStr(arg) GE 8
IFIDNI @SubStr(arg, 1, 7), <OFFSET >
mov eax, arg
reax = -1
ENDIF
ENDIF
IF @SizeStr(arg) GE 10
IFIDNI @SubStr(arg, 1, 9), <LROFFSET >
mov eax, arg
reax = -1
ENDIF
ENDIF
IF NOT reax
IF (OPATTR (arg)) AND 00010000b ;; Is a register value
IFDIFI <arg>, <eax> ;; do not move eax onto itself
mov eax, arg
ret num
reax = -1
ELSE
ret num
ENDIF
ELSEIF (OPATTR (arg)) AND 00000100b ;; Is an immediate value
IF (OPATTR (arg)) AND 00000001b
mov eax, arg
ret num
ELSE
IF arg EQ 0
xor eax, eax
ret num
ELSEIF arg EQ 1
xor eax, eax
inc eax
ret num
ELSEIF arg EQ -1
or eax, NOT 0
ret num
ELSE
mov eax, arg
ret num
ENDIF
ENDIF
reax = -1
ELSE
mov eax, arg
ret num
reax = -1
ENDIF
ENDIF
ENDIF
ENDM
ENDIF
;;------------------------------------------------------------------------------------
;;(MF)翻转参数列表
;;
;;用法 :$ArgRev(参数表)
;;
;;参数 :原参数列表(VARARG)
;
;;返回值:翻转后的参数列表
;
;;影响的寄存器:无
;;
;;------------------------------------------------------------------------------------
IFNDEF $ArgRev
$ArgRev MACRO args:VARARG
LOCAL arg,y
y TEXTEQU <>
FOR arg, <&args>
y CATSTR <arg>, <!,>, y
ENDM
y SUBSTR y, 1, @SizeStr(%y) - 1
EXITM @CatStr(<!<>, y, <!>>)
ENDM
ENDIF
;;------------------------------------------------------------------------------------
;;(MA)快速调用
;;
;;用法 :fastcall 函数名, 参数1, 参数2, ....
;;
;;参数 :函数名+参数列表
;;
;;影响的寄存器:eax, ecx, edx(必须改变)
;;
;;------------------------------------------------------------------------------------
IFNDEF fastcall
fastcall MACRO api:REQ, p1, p2, px:VARARG
LOCAL arg, line, recx, reax, redx
recx = 0
reax = 0
redx = 0
ELSE
IFIDNI <arg>, <eax> ;;Do not overwrite eax
IF reax
line TEXTEQU %@Line
% ECHO @FileCur(line) : ERROR! EAX register value overwritten by fastcall macro.
.ERR
ELSE
push arg
ENDIF
ELSE
push arg
ENDIF
ENDIF
ENDM
ENDIF
IFNB <p1>
IF @SizeStr(<p1>) GE 6
IFIDNI @SubStr(<p1>, 1, 5), <ADDR >
% lea ecx, @SubStr(<p1>, 6)
recx = -1
ENDIF
ENDIF
IF @SizeStr(<p1>) GE 8
IFIDNI @SubStr(<p1>, 1, 7), <OFFSET >
mov ecx, p1
recx = -1
ENDIF
ENDIF
IF @SizeStr(<p1>) GE 10
IFIDNI @SubStr(<p1>, 1, 9), <LROFFSET >
mov ecx, p1
recx = -1
ENDIF
ENDIF
IF (NOT recx)
IF (OPATTR (p1)) AND 00000100b ;; Is an immediate value
IF (OPATTR (p1)) AND 00000001b
mov ecx, p1
ELSE
IF p1 EQ 0
xor ecx, ecx
ELSEIF p1 EQ 1
xor ecx, ecx
inc ecx
ELSEIF p1 EQ -1
or ecx, -1
ELSE
mov ecx, p1
ENDIF
ENDIF
recx = -1
ELSEIF (OPATTR (p1)) AND 00010000b ;; Is a register value
IFDIFI <p1>, <ecx>
IFIDNI <p1>, <eax>
IF reax
line TEXTEQU %@Line
% ECHO @FileCur(line) : ERROR! EAX register value has changed.
.ERR
ENDIF
ENDIF
mov ecx, p1
recx = -1 ;; no more ecx
ENDIF
ELSE
mov ecx, p1
recx = -1
ENDIF
ENDIF
ENDIF
IFNB <p2>
IF @SizeStr(<p2>) GE 6
IFIDNI @SubStr(<p2>, 1, 5), <ADDR >
% lea edx, @SubStr(<p2>, 6)
redx = -1
ENDIF
ENDIF
IF @SizeStr(<p2>) GE 8
IFIDNI @SubStr(<p2>, 1, 7), <OFFSET >
mov edx, p2
redx = -1
ENDIF
ENDIF
IF @SizeStr(<p2>) GE 10
IFIDNI @SubStr(<p2>, 1, 9), <LROFFSET >
mov edx, p2
redx = -1
ENDIF
ENDIF
IF (NOT redx)
IF (OPATTR (p2)) AND 00010000b ;; Is a register value
IFDIFI <p2>, <edx> ;; do not move edx onto itself
IFIDNI <p2>, <eax>
IF reax
line TEXTEQU %@Line
% ECHO @FileCur(line) : ERROR! EAX register value has changed.
.ERR
ENDIF
ENDIF
IFIDNI <p2>, <ecx>
IF recx ;; if ecx was used report error
line TEXTEQU %@Line
% ECHO @FileCur(line) : ERROR! ECX register value has changed.
.ERR
ENDIF
ENDIF
mov edx, p2
redx = -1
ENDIF
ELSEIF (OPATTR (p2)) AND 00000100b ;; Is an immediate value
IF (OPATTR (p2)) AND 00000001b
mov ecx, p2
ELSE
IF p2 EQ 0
xor edx, edx
ELSEIF p2 EQ 1
xor edx, edx
inc edx
ELSEIF p2 EQ -1
or edx, -1
ELSE
mov edx, p2
ENDIF
ENDIF
redx = -1
ELSE
mov edx, p2
redx = -1
ENDIF
ENDIF
ENDIF
