From 34d7fee8dcec1e4e67e77f856fbc5126d95575a4 Mon Sep 17 00:00:00 2001
From: Kwarde <kevin@kwarde.com>
Date: Thu, 10 Jul 2025 11:42:35 +0200
Subject: [PATCH] Adds tolower(), toupper()

---
 src/core.asm  |  36 ++++++++++++++++
 src/tests.asm | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 150 insertions(+)

diff --git a/src/core.asm b/src/core.asm
index 5339070..e4a22ba 100644
--- a/src/core.asm
+++ b/src/core.asm
@@ -4,6 +4,8 @@ section .text
 	global	exit
 	global	islower
 	global	isupper
+	global	tolower
+	global	toupper
 
 ;----- exit(exit_code) -----;
 ; Exits the program with given exit code
@@ -47,3 +49,37 @@ isupper:
 	mov	rax, 1
 	.quit:
 	ret
+
+;----- tolower(c) -----;
+; Converts given ASCII character to lowercase if it is uppercase
+; Return value: Converted lowercase ASCII character or the original input if it wasn't uppercase
+; Used registers:
+;	rax*	(ret)
+;	rdi	(arg)
+tolower:
+	call	isupper
+	test	al, al
+	jnz	.makelow
+	mov	rax, rdi
+	ret
+	.makelow:
+	mov	rax, rdi
+	add	rax, 32
+	ret
+
+;----- toupper(c) -----;
+; Converts given ASCII character to uppercase if it is lowercase
+; Return value: Converted uppercase ASCII character or the original input if it wasn't lowercase
+; Used registers:
+;	rax*	(ret)
+;	rdi	(arg)
+toupper:
+	call	islower
+	test	al, al
+	jnz	.makeupp
+	mov	rax, rdi
+	ret
+	.makeupp:
+	mov	rax, rdi
+	sub	rax, 32
+	ret
diff --git a/src/tests.asm b/src/tests.asm
index d2c6d65..7b8ea43 100644
--- a/src/tests.asm
+++ b/src/tests.asm
@@ -4,6 +4,8 @@
 extern	exit
 extern	islower
 extern	isupper
+extern	tolower
+extern	toupper
 ; console.asm
 extern	print
 extern	puts
@@ -31,6 +33,8 @@ section .rodata
 	TEST_strclr		equ	1
 	TEST_islower		equ	1
 	TEST_isupper		equ	1
+	TEST_tolower		equ	1
+	TEST_toupper		equ	1
 	TEST_strcmp		equ	1
 
 	str1			db	"Hello, world!",EOS
@@ -114,6 +118,20 @@ section .rodata
 	isupper4		db	TAB,"isupper('D'): %d",NL,EOS
 	isupper5		db	TAB,"isupper('!'): %d",NL,EOS
 
+	; tolower()
+	msgTolower		db	NL,"TEST tolower()",NL,EOS
+	tolower1		db	TAB,"tolower(str1[0]): %c",NL,EOS
+	tolower2		db	TAB,"tolower(str1[1]): %c",NL,EOS
+	tolower3		db	TAB,"tolower('!'): %c",NL,EOS
+	tolower4		db	TAB,"tolower() -- entire str4: %s",NL,EOS
+
+	; toupper()
+	msgToupper		db	NL,"TEST tolower()",NL,EOS
+	toupper1		db	TAB,"toupper(str1[0]): %c",NL,EOS
+	toupper2		db	TAB,"toupper(str1[1]): %c",NL,EOS
+	toupper3		db	TAB,"toupper('!'): %c",NL,EOS
+	toupper4		db	TAB,"toupper() -- entire str4: %s",NL,EOS
+	
 	; strcmp()
 	msgStrcmp		db	NL,"TEST strcmp()",NL,EOS
 	strcmp1			db	TAB,"strcmp(str1, str1): %d",NL,EOS
@@ -512,6 +530,102 @@ _start:
 	call	printf
 %endif
 
+;---
+;--- tolower()
+;---
+%if TEST_tolower
+	lea	rdi, [rel msgTolower]
+	call	print
+
+	; TEST 1
+	mov	dil, byte [str1]
+	call	tolower
+	lea	rdi, [rel tolower1]
+	mov	rsi, rax
+	call	printf
+
+	; TEST 2
+	mov	dil, byte [str1 + 1]
+	call	tolower
+	lea	rdi, [rel tolower2]
+	mov	rsi, rax
+	call	printf
+
+	; TEST 3
+	mov	dil, '!'
+	call	tolower
+	lea	rdi, [rel tolower3]
+	mov	rsi, rax
+	call	printf
+
+	; TEST 4
+	lea	rdi, [rel strBuff1]
+	lea	rsi, [rel str4]
+	mov	rdx, 32
+	call	strcpy
+	mov	rdi, rax
+	call	strlen
+	mov	rcx, rax
+	lea	rsi, [rel strBuff1]
+	.tolowerLoop:
+		mov	dil, byte [rsi]
+		call	tolower
+		mov	byte [rsi], al
+		inc	rsi
+		loop	.tolowerLoop
+	lea	rdi, [rel tolower4]
+	lea	rsi, [rel strBuff1]
+	call	printf
+%endif
+
+;---
+;--- toupper()
+;---
+%if TEST_toupper
+	lea	rdi, [rel msgToupper]
+	call	print
+
+	; TEST 1
+	mov	dil, byte [str1]
+	call	toupper
+	lea	rdi, [rel toupper1]
+	mov	rsi, rax
+	call	printf
+
+	; TEST 2
+	mov	dil, byte [str1 + 1]
+	call	toupper
+	lea	rdi, [rel toupper2]
+	mov	rsi, rax
+	call	printf
+
+	; TEST 3
+	mov	dil, '!'
+	call	toupper
+	lea	rdi, [rel toupper3]
+	mov	rsi, rax
+	call	printf
+
+	; TEST 4
+	lea	rdi, [rel strBuff1]
+	lea	rsi, [rel str4]
+	mov	rdx, 32
+	call	strcpy
+	mov	rdi, rax
+	call	strlen
+	mov	rcx, rax
+	lea	rsi, [rel strBuff1]
+	.toupperLoop:
+		mov	dil, byte [rsi]
+		call	toupper
+		mov	byte [rsi], al
+		inc	rsi
+		loop	.toupperLoop
+	lea	rdi, [rel toupper4]
+	lea	rsi, [rel strBuff1]
+	call	printf
+%endif
+
 ;---
 ;--- strcmp()
 ;---