From cae828bc9aba566113b8a67df2471336df5263d5 Mon Sep 17 00:00:00 2001
From: Kwarde <kevin@kwarde.com>
Date: Mon, 14 Jul 2025 13:48:40 +0200
Subject: [PATCH] printf: Add support for \n and \t

---
 src/console.asm | 35 +++++++++++++++++++++++++++++++++++
 src/tests.asm   |  3 ++-
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/src/console.asm b/src/console.asm
index 3f62454..c894ffc 100644
--- a/src/console.asm
+++ b/src/console.asm
@@ -75,6 +75,10 @@ puts:
 ;	*0N*	Pad left with zeroes, N chars (maximum 64). Supported *: d, i, u, x, X, b
 ; <!> Unsupported specifiers are printed as-is
 ; <!> For all specifiers (except %%) an argument is expected. Mismatch between arguments given and specifiers provided will lead to issues
+;
+; Supported special characters:
+;	\n	New line
+;	\t	Tab
 ; Used registers:
 ;	rax*	(ret) amount of printed characters
 ;	rdi*	(arg) pointer to format[] to format and print >> pointer to buffer
@@ -143,6 +147,8 @@ printf:
 		cmp	r10, printfBuffLen-1
 		je	.flushBuffer
 		.flushReturn_0:
+		cmp	byte [rdi], '\'
+		je	.asciiReplacement
 		cmp	byte [rdi], '%'
 		je	.argReplacement
 		mov	r8b, [rdi]
@@ -152,6 +158,32 @@ printf:
 		inc	rdi
 		jmp	.process
 
+		;-- Replace special characters --;
+		.asciiReplacement:
+		cmp	byte [rdi + 1], EOS
+		je	.wrapup
+		mov	r8, NL
+		cmp	byte [rdi + 1], 'n'
+		cmove	r9, r8
+		je	.replaceAscii
+		mov	r8, TAB
+		cmp	byte [rdi + 1], 't'
+		cmove	r9, r8
+		je	.replaceAscii
+
+		jmp	.invalidReplacement
+		.replaceAscii:
+		mov	r8b, r9b
+		mov	r9b, 2
+		cmp	r10, printfBuffLen-1
+		je	.flushBuffer
+		.flushReturn_2:
+		mov	[printfBuff + r10], r8b
+		add	rdi, 2
+		inc	r10
+		jmp	.process
+
+		;-- Replace specifiers --;
 		.argReplacement:
 		cmp	byte [rdi + 1], EOS
 		je	.wrapup
@@ -216,6 +248,7 @@ printf:
 		je	.rep_s
 
 		;--- Invalid ---;
+		.invalidReplacement:
 		mov	r9w, word [rdi]
 		mov	[printfBuff+r10], r9w
 		add	rdi, 2
@@ -346,6 +379,8 @@ printf:
 	je	.flushReturn_0
 	cmp	r9b, 1
 	je	.flushReturn_1
+	cmp	r9b, 2
+	je	.flushReturn_2
 
 	.wrapup:
 	mov	rax, NR_write
diff --git a/src/tests.asm b/src/tests.asm
index 9df0d36..08a331b 100644
--- a/src/tests.asm
+++ b/src/tests.asm
@@ -104,7 +104,7 @@ section .rodata
 	printf11		db	TAB,"printf(",DQUO,"%X | %8X | %08X\n",DQUO,", 0xAB0F, 0xBA0F, 0xAB0F): ",NL,TAB,TAB,EOS
 	printf11Str		db	"%X | %8X | %08X",NL,EOS
 	printf12		db	TAB,"rax=0x1234567890ABCDEF",NL,TAB,"printf(",DQUO,"\nRAX = %064b\nEAX = %64b\n AX = %56b        \n AH = %64b\n AL = %64b\n",DQUO,", rax, eax, ax, ah, al): ",NL,TAB,TAB,EOS
-	printf12Str		db	NL,"RAX = %064b",NL,"EAX = %64b",NL," AX = %64b",NL," AH = %56b        ",NL," AL = %64b",NL,EOS
+	printf12Str		db	"\nRAX = %064b\nEAX = %64b\n AX = %64b\n AH = %56b\t\n AL = %64b\n",EOS
 
 	; strlen()
 	msgStrlen		db	NL,"TEST strlen()",NL,EOS
@@ -834,6 +834,7 @@ _start:
 	call	printf
 
 	; TEST 6
+
 	lea	rdi, [rel str1]
 	lea	rsi, [rel str5]
 	call	strcmp