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