Adds strclr()

src/string.asm

@@ -4,6 +4,7 @@ section .text
 	global	strlen
 	global	strcpy
 	global	strcat
+	global	strclr
 
 ;----- strlen(*str[]) -----;
 ; Gets the length of given string
@@ -85,3 +86,19 @@ strcat:
 	mov	byte [rdi], EOS
 	mov	rax, r8
 	ret
+
+;----- strclr(*str[], maxLength) -----;
+; Clears a string by placing [maxLength] EOS into string.
+; Thus DANGEROUS function: MAKE SURE maxLength IS SIZE OF str[] - greater values WILL cause issues and eventually crashes
+; Return value: N/A
+; Used registers:
+;	rdi*	(arg) Pointer to str[]
+;	rsi	(arg) Length of str[]
+;	rcx*	Counter for STOSB
+;	rax*	Character storage (AL) for STOSB
+strclr:
+	mov	rcx, rsi
+	xor	al, al
+	cld
+	rep	stosb
+	ret

src/tests.asm

@@ -10,15 +10,17 @@ extern	printf
 extern	strlen
 extern	strcpy
 extern	strcat
+extern	strclr
 ; convert.asm
 
 section .rodata
-	TEST_print		equ	1
+	TEST_print		equ	0
-	TEST_puts		equ	1
+	TEST_puts		equ	0
-	TEST_printf		equ	1
+	TEST_printf		equ	0
-	TEST_strlen		equ	1
+	TEST_strlen		equ	0
-	TEST_strcpy		equ	1
+	TEST_strcpy		equ	0
-	TEST_strcat		equ	1
+	TEST_strcat		equ	0
+	TEST_strclr		equ	1
 
 	str1			db	"Hello, world!",EOS
 	str2			db	"Hello, World!",EOS
@@ -57,6 +59,12 @@ section .rodata
 	strcat1			db	TAB,"strcat(strBuff2, str1, 32): ",NL,TAB,TAB,EOS
 	strcat2			db	TAB,"strcat(strBuff2, str5, 32): ",NL,TAB,TAB,EOS
 
+	;strclr()
+	msgStrclr		db	"TEST strclr()",NL,EOS
+	strclr1a		db	TAB,"strcat(strBuff1, str5, 32)",NL,TAB,"strclr(strBuff1, 32)",NL,TAB,"print(strBuff1): ",NL,TAB,TAB,EOS
+	strclr1b		db	TAB,"print(strBuff1[3]): ",NL,TAB,TAB,EOS
+	strclr2			db	TAB,"strcat(strBuff1, str5, 32)",NL,TAB,"strclr(strbuff1, 2)",NL,TAB,"print(strbuff1[3]): ",NL,TAB,TAB,EOS
+
 section .data
 
 section .bss
@@ -193,6 +201,47 @@ _start:
 	call	puts
 %endif
 
+;---
+;--- strclr
+;---
+%if TEST_strclr
+	lea	rdi, [rel msgStrclr]
+	call	print
+
+	; TEST 1
+	lea	rdi, [rel strclr1a]
+	call	print
+	lea	rdi, [rel strBuff1]
+	lea	rsi, [rel str5]
+	mov	rdx, 32
+	call	strcat
+	lea	rdi, [rel strBuff1]
+	mov	rsi, 32
+	call	strclr
+	lea	rdi, [rel strBuff1]
+	call	puts
+
+	lea	rdi, [rel strclr1b]
+	call	print
+	lea	rdi, [rel strBuff1]
+	add	rdi, 3
+	call	puts
+
+	; TEST 2
+	lea	rdi, [rel strclr2]
+	call	print
+	lea	rdi, [rel strBuff1]
+	lea	rsi, [rel str5]
+	mov	rdx, 32
+	call	strcat
+	lea	rdi, [rel strBuff1]
+	mov	rsi, 2
+	call	strclr
+	lea	rdi, [rel strBuff1]
+	add	rdi, 3
+	call puts
+%endif
+
 ;---
 ;--- exit()
 ;---