tolower(), toupper()

core.asm

@@ -5,6 +5,8 @@ section	.text
 	global	maxu
 	global	islower
 	global	isupper
+	global	tolower
+	global	toupper
 
 ;----- min(int a, int b) -----;
 ; return value: lowest value
@@ -86,3 +88,37 @@ isupper:
 	.quit:
 	leave
 	ret
+;----- tolower(char* c) -----;
+; return value: ASCII value. Same as original if it was not an uppercase letter, otherwise lowercase letter
+tolower:
+	push	rbp
+	mov	rbp, rsp
+
+	xor	rax, rax
+	call	isupper
+	mov	rcx, rax
+	mov	al, byte [rdi]
+	cmp	rcx, 1
+	je	.dtl
+	.dtl:
+	add	al, 32
+
+	leave
+	ret
+;----- toupper(char* c) -----;
+; return value: ASCII value. Same as original if it was not a lowercase letter, otherwise uppercase letter
+toupper:
+	push	rbp
+	mov	rbp, rsp
+
+	xor	rax, rax
+	call	islower
+	mov	rcx, rax
+	mov	al, byte [rdi]
+	cmp	rcx, 1
+	je	.dtu
+	.dtu:
+	sub	al, 32
+
+	leave
+	ret

tests.asm

@@ -7,6 +7,8 @@ extern	max
 extern	maxu
 extern	islower
 extern	isupper
+extern	tolower
+extern	toupper
 ;console.asm
 extern	print
 extern	puts
@@ -41,6 +43,8 @@ section	.rodata
 	msgStrcpy	db	"strcpy(str1Copy, str1): %s",10,0
 	msgStrcat	db	"strcat(str1Copy, str3): %s",10,0
 	msgStrlen3	db	"strlen(str1Copy): %d",10,0
+	msgTolower	db	"tolower(str1[0]): %c",10,0
+	msgToupper	db	"toupper(str1[1]): %c",10,0
 section	.data
 section	.bss
 	str1Copy	resb	32
@@ -194,5 +198,21 @@ main:
 	lea	rdi, [rel msgStrlen3]
 	call	printf
 
+	; TEST: tolower(str1[0])
+	lea	rdi, [rel str1]
+	call	tolower
+	mov	rsi, rax
+	xor	rax, rax
+	lea	rdi, [rel msgTolower]
+	call	printf
+
+	; TEST: toupper(str1[1])
+	lea	rdi, [rel str1+1]
+	call	toupper
+	mov	rsi, rax
+	xor	rax, rax
+	lea	rdi, [rel msgToupper]
+	call	printf
+
 	leave
 	ret