printf(): Start adding padding support (right now just detect it and calculate padding length)

src/PRINTF_PADDING_TEST.asm

@@ -0,0 +1,10 @@
+%include "src/constants.asm"
+extern printf
+section .rodata
+	msg	db	"%133769666b",NL,EOS
+section .text
+	global _start
+_start:
+	lea	rdi, [rel msg]
+	mov	rsi, 6
+	call	printf

src/console.asm

@@ -83,6 +83,7 @@ puts:
 ;	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)
+;	r12	Padding for numbers (0=nopadding, >0=padding w/ spaces, NOT >0=padding w/ zeroes)
 printf:
 	%macro load_arg 1
 	cmp	rdx, 4
@@ -147,6 +148,49 @@ printf:
 		je	.wrapup
 		cmp	byte [rdi + 1], '%'
 		je	.rep_pct
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+		cmp	byte [rdi + 1], '1' ;zero padding later!
+		jb	.noPadding
+		cmp	byte [rdi + 1], '9'
+		jg	.noPadding
+		
+		inc	rdi ;point to after '%'
+		xor	rcx, rcx ;length of padding number (set to 0 first)
+		.findPaddingNumLen:
+			cmp	byte [rdi], EOS
+			je	.wrapup
+			cmp	byte [rdi], '0'
+			jb	.getPadding
+			cmp	byte [rdi], '9'
+			ja	.getPadding
+			inc	rcx
+			inc	rdi
+			jmp	.findPaddingNumLen
+		.getPadding:
+		dec	rdi ;dont break .noPadding below (for cmp rdi+1)
+		push	rdi
+		push	rax
+		xor	rax, rax
+		xor	r12, r12 ;total len
+		mov	r9, 1
+		.getPaddingLoop:
+			xor	rax, rax
+			mov	al, byte [rdi]
+			sub	al, '0'
+			imul	r9
+			add	r12, rax
+			dec	rdi
+			mov	rax, r9
+			mov	r9, 10
+			imul	r9
+			mov	r9, rax
+			loop	.getPaddingLoop
+		pop	rax
+		pop	rdi ;r12 should now store padding length
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+		; OK so at this point, padding (spaces, zeroes not yet supported) length is calculated correctly and string is replaced correctly.
+		; Now what remains is to actually add the spaces (and zeroes, eventually)
+		.noPadding:
 		cmp	byte [rdi + 1], 'c'
 		je	.rep_c
 		cmp	byte [rdi + 1], 'i'
@@ -298,5 +342,6 @@ printf:
 	xor	rax, rax
 
 	.quit:
+	pop	r12
 	leave
 	ret