Optimize and improve behavior of gfx_PrintInt and gfx_PrintUInt

Rather than the length argument specifying the exact number of digits
to print, it now specifies the minimum number of characters to print.
This results in the following changes in behavior:

 * If the number to be printed would exceed the specified length, it is
   still printed in full. Previously, the calculation of the first
   digit would overflow instead and print a garbage character, possibly
   taking a long time to do so.
 * For gfx_PrintInt, the minus sign for negative numbers counts toward
   the length. This has the effect that positive and negative values
   that don't exceed the specified length will be padded to the same
   total length, including the minus sign.

Implements #153.

Author: runer112

src/graphx/graphx.asm

@@ -3012,7 +3012,7 @@ _DrawCharacters:
 	or	a,a
 	ret	z
 	call	_PrintChar
-PrintChar_3 = $-3
+PrintChar_2 = $-3
 	inc	hl			; move to the next one
 	jr	_DrawCharacters
 
@@ -3085,8 +3085,6 @@ gfx_SetTextConfig:
 	ld	hl,PrintChar_1
 	ld	(hl),de
 	ld	hl,PrintChar_2
-	ld	(hl),de
-	ld	hl,PrintChar_3
 	ld	(hl),de			; modify all the interal routines to use the clipped text routine
 	push	bc
 	pop	hl
@@ -3298,79 +3296,87 @@ smcByte _TextHeight
 	pop	hl			; restore hl and stack pointer
 	ret
 
+;-------------------------------------------------------------------------------
+gfx_PrintInt:
+; Places an int at the current cursor position
+; Arguments:
+;  arg0 : Number to print
+;  arg1 : Number of characters to print
+; Returns:
+;  None
+	pop	de
+	pop	hl
+	push	hl
+	push	de
+	add	hl,hl
+	db	$3E			; xor a,a -> ld a,*
+
 ;-------------------------------------------------------------------------------
 gfx_PrintUInt:
 ; Places an unsigned int at the current cursor position
 ; Arguments:
 ;  arg0 : Number to print
-;  arg1 : Number of characters to print
+;  arg1 : Minimum number of characters to print
 ; Returns:
 ;  None
-	ld	iy,0
-	add	iy,sp
-	ld	hl,(iy+3)		; hl = uint
-	ld	c,(iy+6)		; c = num chars
-_PrintUInt:
-	ld	a,8
-	sub	a,c
-	ret	c			; make sure less than 8
-	rla
-	rla
-	rla
-	ld	(.offset),a		; select the jump we need
-	jr	$
-.offset = $-1
-	ld	bc,-10000000
+	xor	a,a
+	pop	de
+	pop	hl			; hl = uint
+	pop	bc			; c = min num chars
+	push	bc
+	push	hl
+	push	de
+	jr	nc,.begin		; c ==> actually a negative int
+	ex	de,hl
+	or	a,a
+	sbc	hl,hl
+	sbc	hl,de			; hl = -int
+	ld	a,'-'
+	call	.printchar
+	dec	c
+	jr	nz,.begin
+	inc	c
+.begin:
+	ld	de,-10000000
 	call	.num1
-	ld	bc,-1000000
+	ld	de,-1000000
 	call	.num1
-	ld	bc,-100000
+	ld	de,-100000
 	call	.num1
-	ld	bc,-10000
+	ld	de,-10000
 	call	.num1
-	ld	bc,-1000
+	ld	de,-1000
 	call	.num1
-	ld	bc,-100
+	ld	de,-100
 	call	.num1
-	ld	bc,-10
+	ld	de,-10
 	call	.num1
-	ld	bc,-1
+	ld	de,-1
 .num1:
-	ld	a,'0'-1
+	xor	a,a
 .num2:
 	inc	a
-	add	hl,bc
+	add	hl,de
 	jr	c,.num2
-	sbc	hl,bc
-	jp	_PrintChar		; print the character needed
-PrintChar_1 := $-3
-
-;-------------------------------------------------------------------------------
-gfx_PrintInt:
-; Places an int at the current cursor position
-; Arguments:
-;  arg0 : Number to print
-;  arg1 : Number of characters to print
-; Returns:
-;  None
-	ld	iy,0
-	lea	bc,iy
-	add	iy,sp
-	ld	c,(iy+6)		; c = num chars
-	ld	hl,(iy+3)		; hl = int
-	bit	7,(iy+5)		; if negative
-	jr	z,.positive
+	sbc	hl,de
+	dec	a			; a = next digit
+	jr	nz,.printdigit		; z ==> digit is zero, maybe don't print
+	ld	a,c
+	inc	c
+	cp	a,8
+	ret	c			; nc ==> a digit has already been
+					;        printed, or must start printing
+					;        to satisfy min num chars
+	xor	a,a
+.printdigit:
+	add	a,'0'
+	ld	c,a			; mark that a digit has been printed
+.printchar:
 	push	bc
-	push	hl
-	pop	bc
-	sbc	hl,hl
-	sbc	hl,bc
-	ld	a,'-'
-	call	_PrintChar		; place negative symbol
-PrintChar_2 := $-3
+	call	_PrintChar
+PrintChar_1 := $-3
 	pop	bc
-.positive:
-	jp	_PrintUInt		; handle integer
+	ret
 
 ;-------------------------------------------------------------------------------
 gfx_GetStringWidth:

src/graphx/graphx.h

@@ -846,24 +846,24 @@ void gfx_PrintChar(const char c);
 /**
  * Prints a signed integer
  *
- * Outputs at the current cursor position.
+ * Outputs at the current cursor position. Padded with leading zeros if
+ * necessary to satisfy the specified minimum length.
  * @param n Integer to print
- * @param length Length of integer character display
+ * @param length Minimum number of characters to print
  * @note By default, no text clipping is performed (configurable with gfx_SetTextConfig)
- * @note Values range from -8388608 to 8388607
- * @note Length must be between 0-8
+ * @note \c length must be between 1 and 8, inclusive
  */
 void gfx_PrintInt(int n, uint8_t length);
 
 /**
  * Prints an unsigned integer
  *
- * Outputs at the current cursor position.
+ * Outputs at the current cursor position. Padded with leading zeros if
+ * necessary to satisfy the specified minimum length.
  * @param n Unsigned integer to print
- * @param length Length of unsigned integer character display
+ * @param length Minimum number of characters to print
  * @note By default, no text clipping is performed (configurable with gfx_SetTextConfig)
- * @note Values range from 0-16777215
- * @note Length must be between 0-8
+ * @note \c length must be between 1 and 8, inclusive
  */
 void gfx_PrintUInt(unsigned int n, uint8_t length);