printf(): Add support for %s, fix buffer flushing (length given was r11, not r10)

src/console.asm

@@ -7,7 +7,7 @@ section .rodata
 	printfBuffLen	equ	128
 section .bss
 	printfBuff	resb	printfBuffLen
-	printfArgs	resq	5
+	printfArgs	resq	5 ;5=>rsi,rdx,rcx,r8,r9
 section .text
 	global	print
 	global	puts
@@ -59,15 +59,17 @@ puts:
 ; Return value: Amount of printed characters
 ; Supported specifiers:
 ;	%%	Literal percentage sign
+;	%s	String
 ; <!> 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
 ; Used registers:
-;	rax	(ret) amount of printed characters
+;	rax*	(ret) amount of printed characters
-;	rdi	(arg) pointer to format[] to format and print
+;	rdi*	(arg) pointer to format[] to format and print
-;	rsi	(optional arg)
+;	rsi*	(optional arg) >> Used for inserting strings to buffer
-;	rdx	(optional arg) >> Keeps track of amount of processed format specifiers
+;	rdx*	(optional arg) >> Keeps track of amount of processed format specifiers
 ;	rcx	(optional arg)
-;	r8	(optional arg) >> Used for moving characters
+;	r8*	(optional arg) >> Used for moving characters
-;	r9	(optional arg) >> Keeps track of where to jump after flushing buffer
+;	r9*	(optional arg) >> Keeps track of where to jump after flushing buffer
 ;	r10*	Keeps track of current index of printfBuff
 ;	r11*	Keeps track of total characters (return value)
 printf:
@@ -78,16 +80,17 @@ printf:
 	cmp	byte [rdi], EOS
 	je	.emptyStr
 
+	; Store arguments to memory - easier to load data + more available registers (= less stack usage)
+	mov	[rel printfArgs + SIZE_QWORD * 0], rsi
+	mov	[rel printfArgs + SIZE_QWORD * 1], rdx
+	mov	[rel printfArgs + SIZE_QWORD * 2], rcx
+	mov	[rel printfArgs + SIZE_QWORD * 3], r8
+	mov	[rel printfArgs + SIZE_QWORD * 4], r9
+
+	xor	rdx, rdx
 	xor	r10, r10
 	xor	r11, r11
 
-	; Store arguments to memory - easier to load data + more available registers (= less stack usage)
-	mov	[printfArgs + SIZE_QWORD * 0], rsi
-	mov	[printfArgs + SIZE_QWORD * 1], rdx
-	mov	[printfArgs + SIZE_QWORD * 2], rcx
-	mov	[printfArgs + SIZE_QWORD * 3], r8
-	mov	[printfArgs + SIZE_QWORD * 4], r9
-
 	.process:
 		cmp	byte [rdi], EOS
 		je	.wrapup
@@ -109,6 +112,8 @@ printf:
 		je	.wrapup
 		cmp	byte [rdi + 1], '%'
 		je	.rep_pct
+		cmp	byte [rdi + 1], 's'
+		je	.rep_s
 
 		;--- Invalid ---;
 		mov	r9w, word [rdi]
@@ -126,21 +131,54 @@ printf:
 		add	r11, 1
 		jmp	.process
 
+		;--- '%s' ---;
+		.rep_s:
+		cmp	rdx, 4
+		ja	.s_fromStack
+		mov	rsi, [printfArgs + SIZE_QWORD * rdx]
+		jmp	.insertString
+		.s_fromStack:
+		lea	rsi, [rbp + RBP_OFFSET_CALLER + ((rdx-5) * SIZE_QWORD)]
+
+		;--- Insert string to buffer ---;
+		.insertString:
+			cmp	byte [rsi], EOS
+			je	.endInsertString
+			mov	r9b, 1
+			cmp	r10, printfBuffLen-1
+			je	.flushBuffer
+			.flushReturn_1:
+			mov	r8b, byte [rsi]
+			mov	[printfBuff + r10], r8b
+			inc	rsi
+			inc	r10
+			inc	r11
+			jmp	.insertString
+		.endInsertString:
+			inc	rdx
+			add	rdi, 2
+			jmp	.process
 
 	.flushBuffer:
+	push	rdi
+	push	rsi
 	push	rdx
 	push	r11
 	mov	rax, NR_write
 	mov	rdi, FD_stdout
 	lea	rsi, [rel printfBuff]
-	mov	rdx, r11
+	mov	rdx, r10
 	syscall
-	pop	r10
+	pop	r11
 	pop	rdx
+	pop	rsi
+	pop	rdi
 	xor	r10, r10
 
 	cmp	r9b, 0
 	je	.flushReturn_0
+	cmp	r9b, 1
+	je	.flushReturn_1
 
 	.wrapup:
 	mov	rax, NR_write

src/tests.asm

@@ -34,8 +34,12 @@ section .rodata
 
 	; printf()
 	msgPrintf		db	"TEST printf()",NL,EOS
-	printf1			db	TAB,"printf(",DQUO,"He%ll%o there%%%%%!%s%!%\n",DQUO,"): ",NL,TAB,TAB,EOS
+	printf1			db	TAB,"printf(",DQUO,"He%ll%o there%%%%%!%!%\n",DQUO,"): ",NL,TAB,TAB,EOS
-	printf1Str		db	"He%ll%o there%%%%%!%s%!%",NL,EOS
+	printf1Str		db	"He%ll%o there%%%%%!%!%",NL,EOS
+	printf2			db	TAB,"printf(",DQUO,"Are %s doing %s?\n",DQUO,", printf2Str1, printf2Str2): ",NL,TAB,TAB,EOS
+	printf2Str		db	"Are %s doing %s?",NL,EOS
+	printf2Str1		db	"you",EOS
+	printf2Str2		db	"okay",EOS
 
 	; strlen()
 	strlenStr1		db	"Hello",EOS
@@ -94,6 +98,14 @@ _start:
 	call	print
 	lea	rdi, [rel printf1Str]
 	call	printf
+
+	; TEST 2
+	lea	rdi, [rel printf2]
+	call	print
+	lea	rdi, [rel printf2Str]
+	lea	rsi, [rel printf2Str1]
+	lea	rdx, [rel printf2Str2]
+	call	printf
 %endif
 
 ;---