Category : Modula II Source Code
Archive   : STRINGS.ZIP
Filename : STRASM.A

module StrAsm

section ; segment C_CODE(CODE,28H); group G_CODE(C_CODE); select C_CODE

public StrAsm$BackArray: sLen = 18; sSeg = 16; sOfs = 14;
dLen = 12; dSeg = 10; dOfs = 8; eLen = 6;

push bp; mov bp,sp
push ds; push es; push si; push di
lds si,[bp][sOfs]
push ss
pop es (* point es to stack *)
mov cx,[bp][eLen] (* for movsb *)
sub sp,cx (* make room for string *)
mov di,sp (* and point di to string *)
rep
movsb (* copy string to stack *)
push ss
pop ds (* point ds to stack segment *)
mov si,sp (* and si to string *)
les di,[bp][dOfs]
mov cx,[bp][eLen] (* recall length *)
add di,cx (* and point to end of string *)
dec di (* where string start = 0 *)
jmp bcopy
bcopy:
lodsb
mov es:[di],al
dec di
loop bcopy
ret:
add sp,[bp][eLen] (* pop off string *)
pop di; pop si; pop es; pop ds
pop bp; ret far 14

section ; segment C_CODE(CODE,28H); group G_CODE(C_CODE); select C_CODE

extrn AsmLib$Length

extrn StrAsm$BackArray

public StrAsm$Reverse: sLen = 16; sSeg = 14; sOfs = 12;
dLen = 10; dSeg = 8; dOfs = 6;
push bp; mov bp,sp
push ds; push es; push si; push di
push [bp][sLen]
push [bp][sSeg]
push [bp][sOfs]
les di,[bp][dOfs]
call far AsmLib$Length
cmp ax,0 (* is string empty? *)
jne continue
mov es:[di],al (* then return empty string *)
jmp ret
continue:
cmp ax,[bp][dLen] (* is source length >= destination size *)
jl less
je equal
mov ax,[bp][dLen] (* if greater, truncate *)
jmp equal
less:
add di,ax (* if less point to end of string *)
mov byte es:[di],0 (* and terminate string *)
equal:
push [bp][sLen]

push [bp][sSeg]
push [bp][sOfs]
push [bp][dLen]
push [bp][dSeg]
push [bp][dOfs]
push ax
call far StrAsm$BackArray
ret:
pop di; pop si; pop es; pop ds
pop bp; ret far 12

end