From 9982eabe7c05e102860d4691a0956f6d08acb91b Mon Sep 17 00:00:00 2001
From: Kwarde <kevin@kwarde.com>
Date: Fri, 27 Jun 2025 18:57:54 +0200
Subject: [PATCH] printf(): Always print full string instead of throwing an
 error; print printfBuff when full and start at index 0 again

---
 src/console.asm | 61 ++++++++++++++++++++++++++++++++++---------------
 1 file changed, 43 insertions(+), 18 deletions(-)

diff --git a/src/console.asm b/src/console.asm
index e328851..64263c7 100644
--- a/src/console.asm
+++ b/src/console.asm
@@ -6,9 +6,7 @@ extern	itoa
 
 section .rodata
 	bNL		db	NL
-	bufferLength	equ	4096
-	ERR_buffLen	db	"<!> ERROR: Failed to complete printf(), reached buffer length!",NL,EOS
-	lERR_buffLen	equ	$-ERR_buffLen-1
+	bufferLength	equ	128
 
 	; Errors (perror)
 	perrorMsg	db	"%s: %s",NL,EOS
@@ -88,8 +86,10 @@ printf:
 	push	rbp
 	mov	rbp, rsp
 
-	push	r12 
-	push	r14
+	push	r12
+	push	r13 ;total length of string
+	push	r14 ;current index of printfBuff
+	push	r15 ;where to return after flush
 
 	xor	r10, r10
 	xor	r14, r14
@@ -97,8 +97,10 @@ printf:
 	.makeStr:
 		cmp	byte [rdi], 0x0
 		je	.finish
+		mov	r15, 1
 		cmp	r14, bufferLength-1
-		je	.finish
+		je	.flush
+		.continue_after_flush_1:
 		cmp	byte [rdi], '%'
 		je	.replaceArg
 		mov	r12b, byte [rdi]
@@ -212,8 +214,10 @@ printf:
 
 			;--- Move fetched data to buffer ---;
 			.insertLoop:
+				mov	r15, 2
 				cmp	r14, bufferLength-1
-				je	.finish
+				je	.flush
+				.continue_after_flush_2:
 				cmp	byte [rsi], 0x0
 				je	.s0f
 				mov	r12b, byte [rsi]
@@ -231,6 +235,34 @@ printf:
 		inc	rdi
 		inc	r11
 		jmp	.makeStr
+
+	.flush:
+	push	rdi
+	push	rsi
+	push	rdx
+	push	rcx
+	push	r8
+	push	r9
+	mov	rax, NR_write
+	mov	rdi, 1
+	lea	rsi, [rel printfBuff]
+	mov	rdx, r14
+	mov	byte [r11], 0x0
+	syscall
+	pop	r9
+	pop	r8
+	pop	rcx
+	pop	rdx
+	pop	rsi
+	pop	rdi
+	add	r13, r14
+	xor	r14, r14
+	lea	r11, [rel printfBuff] 
+
+	cmp	r15, 1
+	je	.continue_after_flush_1
+	cmp	r15, 2
+	je	.continue_after_flush_2
 	
 	.finish:
 	mov	byte [r11], 0x0
@@ -238,19 +270,12 @@ printf:
 	mov	rdi, 1
 	lea	rsi, [rel printfBuff]
 	mov	rdx, r14
+	add	r13, r14
 	syscall
-	mov	rax, r14
-	cmp	r14, bufferLength-1
-	jl	.final
-
-	mov	rax, NR_write
-	mov	rdi, 2
-	lea	rsi, [rel ERR_buffLen]
-	mov	rdx, lERR_buffLen
-	syscall
-
-	.final:
+	mov	rax, r13
+	pop	r15
 	pop	r14
+	pop	r13
 	pop	r12
 
 	leave