The test piece has 2 algos in it, one which is simple that throws away anything over ascii 126 with the option of either simply removing the high ascii character or replacing it with a space.
The second algo is more powerful in that it runs off a table and can use or reject any character apart from the zero and while it is slightly slower, it is probably fast enough in most contexts.
This is the test code, zip file attached.
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include \masm32\include64\masm64rt.inc
.data
tst0 db "1234",174,175,"5678",215,"9012",0
ptst0 dq tst0
tst1 db "1234",174,175,"5678",215,"9012",0
ptst1 dq tst1
text0 db "123",247,"456",156,"789",0
ptxt0 dq text0
text1 db "123",247,"456",156,"789",0
ptxt1 dq text1
.code
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entry_point proc
stdout " ********************",13,10
stdout " fixed low ascii only",13,10
stdout " ********************",13,10
conout ptst0,lf
rcall low_ascii,ptst0,0
conout ptst0," ",chr$(174)," Characters removed",lf
conout ptst1,lf
rcall low_ascii,ptst1,1
conout ptst1," ",chr$(174)," Replaced with space",lf
stdout " ***********************************************",13,10
stdout " flexible character range removal or replacement",13,10
stdout " ***********************************************",13,10
conout ptxt0,lf
rcall str_strip,ptxt0, 0 ; strip text by removal of unwanted characters
conout ptxt0," ",chr$(174)," Characters removed",lf
conout ptxt1,lf
rcall str_strip,ptxt1, 1 ; modify text by replacing unwanted characters with spaces
conout ptxt1," ",chr$(174)," Replaced with space",lf
stdout "-----------------------------------",13,10
waitkey
.exit
entry_point endp
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NOSTACKFRAME
low_ascii proc
; ------------------------------------------
; procedure strips out high ascii characters
; algorithm overwrites original source
; ARGUMENTS
; 1. rcx = address of string to strip
; 2. rdx = optional removal or space
; replacement of high ascii char
; 0 = write nothing in its place
; other = write space in its place
; ------------------------------------------
mov r11, rcx ; load address into r11 as source
mov r10, rcx ; destination is same address
mov r9, rdx ; optional replacement or removal
sub r11, 1
jmp lbl0 ; jump into algo
pre:
test r9, r9 ; test if option 0 is set
jz lbl0 ; if 0, jump past and remove character
mov BYTE PTR [r10], 32 ; else write a space
add r10, 1 ; then increment r10
lbl0:
REPEAT 3
add r11, 1
movzx rax, BYTE PTR [r11] ; zero extend byte to QWORD
cmp rax, 127 ; test if its 127 or greater
jge pre ; jump back to "pre" if it is
mov BYTE PTR [r10], al ; write byte to destination
add r10, 1 ; increment r10
test rax, rax ; test if last byte written is zero
jz lbl1 ; jump to exit if 0
ENDM
add r11, 1
movzx rax, BYTE PTR [r11] ; zero extend byte to QWORD
cmp rax, 127 ; test if its 127 or greater
jge pre ; jump back to "pre" if it is
mov BYTE PTR [r10], al ; write byte to destination
add r10, 1 ; increment r10
test rax, rax ; test if last byte written is zero
jnz lbl0 ; loop back if its not
lbl1:
mov rax, rcx ; return source address
ret ; bye
low_ascii endp
STACKFRAME
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NOSTACKFRAME ; stack frame not required for pure mnemonic procedure
str_strip proc
; -----------------------------------
; strip characters from source as
; determined by character table.
; ===========================
; procedure overwrites source
; ===========================
; source address = rcx
; option value = rdx
; 0 = remove from string
; other = replace with space
; -----------------------------------
mov r11, rcx ; load source address into r11
mov r9, rcx ; same address as destination
lea r10, chtbl ; load the character table address
mov r8, rdx ; load option into r9
sub r11, 1 ; sub 1 to set up byte offset
jmp lbl0 ; jump directly into main loop
pre:
test r8, r8 ; test if optn is 0
jz lbl0 ; jump to main loop if it is
mov BYTE PTR [r9], 32 ; else write a space
add r9, 1 ; increment destination address
lbl0:
add r11, 1
movzx rax, BYTE PTR [r11] ; read byte from source
movzx rdx, BYTE PTR [r10+rax] ; get its value from table
test rdx, rdx ; if 0
jz pre ; branch back to label "pre"
mov BYTE PTR [r9], al ; else write it to destination address
add r9, 1 ; increment destination address
test rax, rax ; test if last byte written in 0
jnz lbl0 ; loop back if not
mov rax, rcx ; return source address
ret ; bye
align 16
chtbl:
db 1,0,0,0,0,0,0,0,0,1,1,0,0,1,0,0 ; 0, 9, 10, 13
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 ; 32 to 126
db 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
db 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
db 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
db 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
db 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ; no high ascii
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
str_strip endp
STACKFRAME ; restore default stack frame
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end