supermacros.asm

; supermacros.asm
;   High-level constructs for NASM
;   v0.5.0 - 01.05.2014

; Take note that these macros are written in CamelCase. This is to distinguish
;then from assembly instructions, which are typically written all in one case.

; Functions ===================================================================

; Begin a function, or rather, the variable declaration part. Functions are
;global by default. Use LocalFunc to make a function that is not visible
;outside of its resident file.
%macro Func 1 ; name
	global %1
%1:
	%push FuncVarList
	%assign ArgCount 0
	%assign LocCount 0
%endmacro

; Identical to Func, only the function will not be visible ouside of the file
;that contains it.
%macro LocalFunc 1 ;name
%1:
	%push FuncVarList
	%assign	ArgCount 0
	%assign LocCount 0
%endmacro

; Define a name for a stack argument. These are be listed in the same order as
;they are in a C function prototype, that is, left-to-right.
%macro Arg 2 ; name, size
	%ifctx FuncVarList
		%xdefine %1 [ebp+(ArgCount+8)]
		%assign ArgCount ArgCount + %2
	%else
		%fatal "`Arg' must be inside function variable list"
	%endif
%endmacro

; Define a name for a local variable and increase the space to be
;allocated on the stack.
%macro Loc 2 ; name, size
	%ifctx FuncVarList
		%xdefine %1 [ebp-(LocCount+8)]
		%assign LocCount LocCount + %2
	%else
		%fatal "`Loc' must be inside function variable list"
	%endif

%endmacro

; Begin the code section of a function. The stack frame is created and space
;for stack variable is allocated, if neccesary.
%macro Body 0
	%ifctx FuncVarList
		%repl FuncBody
		push ebp
		mov ebp, esp
		%if LocCount > 0
			sub	ebp, LocCount
		%endif
	%else
		%fatal "`Body' must be after function argument list"
	%endif
%endmacro

; Set EAX to the return value (if given) and return from the function. If a
;function does not have a Return, it could potentially run off the end into
;the great abyss of unused memory.
%macro Return 0-1 eax ; value
	%ifctx FuncBody
		%repl FuncBodyReturn
	%endif
	%ifctx FuncBodyReturn
		%if %1 != eax
			mov	eax, %1
		%endif
		mov	esp, ebp
		pop	ebp
		%if LocCount > 0
			ret	LocCount
		%else
			ret
		%endif
	%else
		%fatal "`Return' must be inside function body"
	%endif
%endmacro

; End the code section of a function.
%macro EndFunc 0
	%ifctx FuncBodyReturn
		%pop
	%elifctx FuncBody
		%warning "function without a `Return'"
	%else
		%fatal "`Endfunc' must follow `Body'"
	%endif
%endmacro

; Repeat Loops ================================================================

; Start a Repeat loop. Jump back with a While, Until, or Forever.
%macro Repeat 0
	%push Repeat
	%$DO:
%endmacro

; If the condition is true, jump back to the corresponding Do.
%macro While 1 ; condition
	%ifctx Repeat
		j%1	%$DO
		%$BRK:
		%pop
	%else
		%fatal "`While' must match a `Repeat'"
	%endif
%endmacro

; If the condition isn't true, jump back to the corresponding Do.
%macro Until 1
	%ifctx Repeat
		jn%1	%$DO
		%$BRK:
		%pop
	%else
		%fatal "`Until' must match a `Repeat'"
	%endif
%endmacro

; Unconditionally jump back to the corresponding Do.
%macro Forever 0
	%ifctx Repeat
		jmp	%$DO
		%$BRK:
		%pop
	%else
		%fatal "`Forever' must match a `Repeat'"
	%endif
%endmacro

; If the condition is true, jump out of the corresponding Repeat loop.
%macro BreakIf 1
	%ifctx Repeat
		j%1	%$BRK
	%else
		%fatal "`BreakIf' must be inside `Repeat' loop"
	%endif
%endmacro

; If the condition isn't true, jump out of the corresponding Repeat loop.
%macro BreakUnless 1
	%ifctx Repeat
		jn%1	%$BRK
	%else
		%fatal "`BreakUnless' must be inside `Repeat' loop"
	%endif
%endmacro

; Unconditionall jump out of the corresponding Repeat loop.
%macro Break 0
	%ifctx Repeat
		jmp	%$BRK
	%else
		%fatal "`Break' must be inside `Repeat' loop"
	%endif
%endmacro

; If Blocks ===================================================================

; Start an If block. If you're programming in assembly, I expect you know how
;to use an If...EndIf or an If...Else...EndIf structure.
%macro If 1 ; condition
	%push If
	jn%1	%$IFN
%endmacro

%macro Else 0
	%ifctx If
		%repl IfElse
		jmp	%$IFE
		%$IFN:
	%else
		%fatal "`Else' must follow `If'"
	%endif
%endmacro

%macro EndIf 0
	%ifctx If
		%$IFN:
		%pop
	%ifctx IfElse
		%$IFE:
		%pop
	%else
		%fatal "`EndEf' must follow an `If' or an `Else'"
%endmacro