From cef713db149c41d8458be2de122c58d7802f9867 Mon Sep 17 00:00:00 2001
From: Kwarde <kevin@kwarde.com>
Date: Wed, 25 Jun 2025 20:40:35 +0200
Subject: [PATCH] Minor optimizations in printf() (stop using rbx and r13, use
 smarter checks instead + pop r11 correctly (prevent stack corruption))

---
 console.asm | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/console.asm b/console.asm
index 6990b3e..b8ddab8 100644
--- a/console.asm
+++ b/console.asm
@@ -55,12 +55,9 @@ printf:
 	push	rbp
 	mov	rbp, rsp
 
-	push	rbx ; used to check if error must be sent (reached buff len)
 	push	r12 ; used for writing byted to printBuff
-	push	r13 ; (also) used for writing bytes to printBuff (why again? gotta check that out - probably not needed, just lost count of register usage at some point)
 	push	r14 ; count length of printBuff
 
-	xor	rbx, rbx
 	xor	r10, r10
 	xor	r14, r14
 	lea	r11, [rel printfBuff]
@@ -185,7 +182,6 @@ printf:
 			mov	[printfNBuff], dil
 			inc	r14
 			cmp	r14, bufferLength-1
-			; Print error to stdout
 			je	.finish_L
 			mov	dil, 0
 			mov	[printfNBuff+1], dil
@@ -230,8 +226,8 @@ printf:
 				je	.finish_L
 				cmp	byte [rsi], 0x0
 				je	.s0f
-				mov	r13b, byte [rsi]
-				mov	byte [r11], r13b
+				mov	r12b, byte [rsi]
+				mov	byte [r11], r12b
 				inc	r14
 				inc	rsi
 				inc	r11
@@ -255,8 +251,8 @@ printf:
 	call	print
 	lea	rdi, [rel printfBuff]
 	call	strlen
-	test	rbx, rbx
-	jz	.final
+	cmp	r14, bufferLength-1
+	jl	.final
 
 	push	r11
 	mov	rax, NR_write
@@ -264,13 +260,11 @@ printf:
 	lea	rsi, [rel ERR_buffLen]
 	mov	rdx, lERR_buffLen
 	syscall
+	pop	r11
 
 	.final:
-	pop	r11
 	pop	r14
-	pop	r13
 	pop	r12
-	pop	rbx
 
 	leave
 	ret