text.asm

;------ SetTextMode ------------------------------------------------------------
SetTextMode:
; Sets the LCD to 8-bit palette mode
; Inputs:
;  - None
; Output:
;  - LCD mode changed
; Destroys:
;  - Whatever
	ld	hl, ColorPaletteTable
	ld	de, mpLcdPalette
	ld	bc, 32
	ldir
	ld	hl, lcdBpp4 | lcdPwr | lcdBigEndianPixels | lcdBgr
	ld	(mpLcdCtrl), hl
	ret
ColorPaletteTable:
	;	Irrrrrgggggbbbbb
	.dw	0000000000000000b	; 0 0000 Black
	.dw	0000000000011111b	; 1 0001 Blue
	.dw	0000001111100000b	; 2 0010 Green
	.dw	0000001000010000b	; 3 0011 Teal
	.dw	0111110000000000b	; 4 0100 Red
	.dw	0100000000010000b	; 5 0101 Purple
	.dw	0100001000000000b	; 6 0110 Amber
	.dw	0011110111101111b	; 7 0111 Dark Gray
	.dw	0110001100011000b	; 8 1000 Light Gray
;	.db	11101 110b, 110 10101b	; 9 1001 Light Blue
	.dw	0101011101111101b	; 9 1001 Light Blue
	.dw	1000011111110000b	; A 1010 Light Green
	.dw	1000001111111111b	; B 1011 Cyan
	.dw	1111111000010000b	; C 1100 Pink
	.dw	1111110000011111b	; D 1101 Magenta
	.dw	1111111111100000b	; E 1110 Yellow
	.dw	1111111111111111b	; F 1111 White
colorBlack		.equ	0000b
bgColorBlack		.equ	(colorBlack << 4)
colorBlue		.equ	0001b
bgColorBlue		.equ	(colorBlue << 4)
colorGreen		.equ	0010b
bgColorGreen		.equ	(colorGreen << 4)
colorTeal		.equ	0011b
bgColorTeal		.equ	(colorTeal << 4)
colorRed		.equ	0100b
bgColorRed		.equ	(colorRed << 4)
colorPurple		.equ	0101b
bgColorPurple		.equ	(colorPurple << 4)
colorAmber		.equ	0110b
bgColorAmber		.equ	(colorAmber << 4)
colorDarkGray		.equ	0111b
bgColorDarkGray		.equ	(colorDarkGray << 4)
colorLightGray		.equ	1000b
bgColorLightGray	.equ	(colorLightGray << 4)
colorLightBlue		.equ	1001b
bgColorLightBlue	.equ	(colorLightBlue << 4)
colorLightGreen		.equ	1010b
bgColorLightGreen	.equ	(colorLightGreen << 4)
colorCyan		.equ	1011b
bgColorCyan		.equ	(colorCyan << 4)
colorPink		.equ	1100b
bgColorPink		.equ	(colorPink << 4)
colorMagenta		.equ	1101b
bgColorMagenta		.equ	(colorMagenta << 4)
colorYellow		.equ	1110b
bgColorYellow		.equ	(colorYellow << 4)
colorWhite		.equ	1111b
bgColorWhite		.equ	(colorWhite << 4)


;------ FixLcdMode -------------------------------------------------------------
FixLcdMode:
; Fixes the LCD mode and other settings for the OS's benefit.
; Inputs:
;  - None
; Output:
;  - LCD mode changed
; Destroys:
;  - Whatever
	ld	hl, lcdNormalMode
	ld	(mpLcdCtrl), hl
	ld	hl, vRam
	ld	(mpLcdBase), hl
	ret


;------ LoadFont ---------------------------------------------------------------
LoadFont:
; Sets up font info struct
; Inputs:
;  - HL: Pointer to font
; Outputs:
;  - Font ready for use with PutC
;  - Don't forget to SetColors during initialization
; Destroys:
;  - AF
;  - BC
;  - DE
;  - HL
	push	ix
	ld	a, (hl)
	ld	(fontHeight), a
	push	hl
	pop	ix
	ld	de, (ix + 1)
	add	hl, de
	ld	(fontWidthsPtr), hl
	sbc	hl, de
	ld	de, (ix + 4)
	add	hl, de
	ld	(fontDataPtr), hl
	pop	ix
	ret


;------ ClearScreen ------------------------------------------------------------
ClrScrnFull:
ClearScreen:
	ld	de, (mpLcdBase)
	or	a
	sbc	hl, hl
	ld	(lcdRow), hl
	ld	(lcdCol), hl
	add	hl, de
	inc	de
	ld	(hl), 0
	ld	bc, ((320 * 240) / 2) - 1
	ldir
	ret


;------ NewLine ----------------------------------------------------------------
NewLine:
; Moves cursor to next line.
; Inputs:
;  - (lcdCol), (lcdRow)
; Outputs:
;  - Cursor adjusted
;  - DE = 0
;  - HL has old value of DE
; Destroys:
;  - AF
;  - B
	push	hl
	or	a
	sbc	hl, hl
	ld	(lcdCol), hl
	ex	de, hl
	ld	a, (fontHeight)
	ld	b, a
	ld	a, (lcdRow)
	add	a, b
	ld	(lcdRow), a
	add	a, b
	cp	240
	pop	hl
	ret	c
	; Glyph will extend past bottom of screen, so force wrap
	xor	a
	ld	(lcdRow), a
	ret


;------ PutS -------------------------------------------------------------------
PutS:
; Displays a string.  If the string contains control codes, those codes are
; parsed.
; Input:
;  - HL: String to show
; Output:
;  - String shown
;  - HL advanced to the byte after the null terminator.
; Destroys:
;  - AF
	ld	a, (hl)
	inc	hl
	or	a
	scf
	ret	z
	cp	chNewLine
	jr	z, putSNewLine
	
	push	hl
	push	de
	call	GetGlyphWidth
	sbc	hl, hl	; C is reset from GetGlyphWidth
	ld	l, a
	ld	de, (lcdCol)
	add	hl, de	; C is reset
	ld	de, 320 - 1
	sbc	hl, de
	pop	de
	pop	hl
	dec	hl
	jr	nc, putSNewLine
	
	ld	a, (hl)
	inc	hl
	call	PutC
	jr	PutS
putSNewLine:
	push	hl
;	call	ClearEOL
	ld	a, (lcdRow)
	add	a, 14
	cp	240 - 14
	jr	c, +_
	xor	a
_:	ld	(lcdRow), a
	or	a
	sbc	hl, hl
	ld	(lcdCol), hl
	pop	hl
	jr	PutS


;------ GetCursorPtr -----------------------------------------------------------
GetCursorPtr:
; Computes the address the LCD cursor is referencing.
; Inputs:
;  - (lcdRow), (lcdCol)
; Outputs:
;  - HL: Pointer
; Destroys:
;  - Nothing
	push	de
	ld	hl, (lcdRow)
	ld	h, 160
	mlt	hl
	add	hl, hl
	ld	de, (lcdCol)
	add	hl, de
	ld	de, (mpLcdBase)
	add	hl, de
	pop	de
	ret


;------ SetColors --------------------------------------------------------------
SetColors:
; Sets the foreground and background colors.
; This function must be used instead of loading the value directly because PutC
; uses a cached table for decoding character bitmaps to 4-bit color.
; Inputs:
;  - A: (background << 4) | foreground
; Outputs:
;  - Colors updated
; Destroys:
;  - AF
	; 0		1
	; back << 4 | fore
	push	hl
	push	bc
	ld	hl, textColors + 1
	ld	(hl), a
	ld	b, a
	inc	hl
	rrca
	rrca
	rrca
	rrca
	ld	(hl), a
	inc	hl
	and	0F0h
	ld	c, a
	ld	a, b
	and	0Fh
	or	c
	ld	(hl), a
	dec	hl
	dec	hl
	dec	hl
	ld	a, b
	and	0F0h
	ld	b, a
	rrca
	rrca
	rrca
	rrca
	or	b
	ld	(hl), a
	pop	bc
	pop	hl
	ret


;------ SetForeColor -----------------------------------------------------------
SetForeColor:
; Sets the foreground color.
; This function must be used instead of loading the value directly because PutC
; uses a cached table for decoding character bitmaps to 4-bit color.
; Inputs:
;  - A: foreground
; Outputs:
;  - Colors updated
; Destroys:
;  - AF
	push	hl
	push	bc
	ld	c, a
	rrca
	rrca
	rrca
	rrca
	ld	b, a
	ld	hl, textColors + 1
	ld	a, (hl)
	and	0F0h
	or	c
	ld	(hl), a
	inc	hl
	ld	a, (hl)
	and	0Fh
	or	b
	ld	(hl), a
	inc	hl
	ld	a, b
	or	c
	ld	(hl), a
	pop	bc
	pop	hl
	ret


;------ SetBackColor -----------------------------------------------------------
SetBackColor:
; Sets the background color.
; This function must be used instead of loading the value directly because PutC
; uses a cached table for decoding character bitmaps to 4-bit color.
; Inputs:
;  - A: background (not left shifted), upper nibble must be zero
; Outputs:
;  - Colors updated
; Destroys:
;  - AF
	push	hl
	push	bc
	ld	c, a
	rrca
	rrca
	rrca
	rrca
	ld	b, a
	ld	hl, textColors
	or	c
	ld	(hl), a
	inc	hl
	ld	a, (hl)
	and	0Fh
	or	b
	ld	(hl), a
	inc	hl
	ld	a, (hl)
	and	0F0h
	or	c
	ld	(hl), a
	pop	bc
	pop	hl
	ret


;------ GetGlyphWidth ----------------------------------------------------------
GetGlyphWidth:
; GetGlyphWidth
; Returns the width of the given glyph
; Input:
;  - A: Codepoint
; Output:
;  - A: Width
;  - Carry is reset
; Destroys:
;  - Nothing
	push	hl
	push	de
	or	a
	sbc	hl, hl
	ld	l, a
	ld	de, (fontWidthsPtr)
	add	hl, de
	ld	a, (hl)
	pop	de
	pop	hl
	ret


;------ GetStrWidth ------------------------------------------------------------
GetStrWidth:
; Computes the width, in pixels, of a string
; Input:
;  - HL: Pointer to string
; Output:
;  - HL: Width of string, in pixels
; Destroys:
;  - AF
;  - DE
	ex	de, hl
	or	a
	sbc	hl, hl
	push	hl
	pop	bc
gswl:	ld	a, (de)
	inc	de
	or	a
	ret	z
	call	GetGlyphWidth
	ld	c, a
	add	hl, bc
	jr	gswl


;------ CenterObjectInfo -------------------------------------------------------
CenterObjectInfo:
; Computes location for an object given its size and center location.
; Inputs:
;  - HL: Size
;  - DE: Column to center around
; Output:
;  - HL: Left edge of object
; Destroys:
;  - Flags
	push	de
	srl	h
	rr	l
	ex	de, hl
	or	a
	sbc.sis	hl, de
	pop	de
	ret


;------ CenterTextInfo ---------------------------------------------------------
CenterTextInfo:
; Inputs:
;  - HL: Pointer to string
;  - DE: Column to center around
; Outputs:
;  - BC: String width
;  - DE: Pointer to string
;  - HL: Left edge of string
; Destroys:
;  - AF
	push	hl
	call	GetStrWidth
	push	hl
	pop	bc
	call	CenterObjectInfo
	pop	de
	ret


;------ PutSCentered -----------------------------------------------------------
PutSCentered:
; Displays text centered about a specific location.
; Inputs:
;  - HL: Pointer to string
;  - DE: Column to center around
; Outputs:
;  - BC: String width
;  - DE: Left edge of string
; Destroys:
;  - AF
	call	CenterTextInfo
	ld	(lcdCol), hl
	ex	de, hl
	call	PutS
	ret


;------ PutC -------------------------------------------------------------------
PutC:
; Displays a glyph.
; I hate this function.
; TODO:
;  - Branch into different subfunctions earlier if possible to avoid all those
;    in-loop conditionals.
; Inputs:
;  - A: ASCII code
; Outputs:
;  - Screen updated
; Destroys:
;  - Nothing
; Vars
PutC_Flags		.equ	0
PutC_BytesPerLine	.equ	PutC_Flags + 1
PutC_FinalNibbles	.equ	PutC_BytesPerLine + 1
PutC_GlyphWidth		.equ	PutC_FinalNibbles + 1
PutC_GlyphHeight	.equ	PutC_GlyphWidth + 1
PutC_RowAdvance		.equ	PutC_GlyphHeight + 1
PutC_ColorsCache	.equ	PutC_RowAdvance + 3
PutC_LocalsSize		.equ	PutC_ColorsCache + 4
; Flags
PutC_OddWidth		.equ	0
PutC_OddStart		.equ	1
; Loop unrolling
#macro PUT_C_DO_BYTE()
	lea	hl, iy + PutC_ColorsCache	; One less memory access than LD HL, imm24; same as LD HL, imm16 in Z80 mode
	rlca
	jr	nc, $ + 4
	inc	hl
	inc	hl
	rlca
	jr	nc, $ + 3
	inc	hl
	ldi
#endmacro
#macro	PUT_C_ODD_NIBBLE()
	lea	hl, iy + PutC_ColorsCache
	rlca
	jr	nc, $ + 3
	inc	hl
	ld	c, a
	ex	de, hl
	ld	a, (hl)
	and	0F0h
	ld	(hl), a
	ld	a, (de)
	and	0Fh
	or	(hl)
	ld	(hl), a
	ex	de, hl
;	inc	de
	ld	a, c
#endmacro
#macro	PUT_C_EVEN_NIBBLE()
	lea	hl, iy + PutC_ColorsCache + 1
	rlca
	jr	nc, $ + 3
	inc	hl
	ld	c, a
	ex	de, hl
	ld	a, (hl)
	and	0Fh
	ld	(hl), a
	ld	a, (de)
	and	0F0h
	or	(hl)
	ld	(hl), a
	ex	de, hl
;	inc	de	; Do not increment
	ld	a, c
#endmacro
; Open stack frame
	push	af
	push	bc
	push	de
	push	hl
	push	ix
	push	iy
	ld	iy, -PutC_LocalsSize
	add	iy, sp
	ld	sp, iy
	; Reset flags
	ld	(iy + PutC_Flags), 0
	; Get bitmap ptr
	ld	l, a
	ld	h, 3
	mlt	hl
	ld	de, (fontDataPtr)
	add	hl, de
	ld	ix, (hl)
	add	ix, de
	; Get glyph width
	or	a
	sbc	hl, hl
	ld	l, a
	ld	de, (fontWidthsPtr)
	add	hl, de
	ld	a, (hl)
	ld	(iy + PutC_GlyphWidth), a
	; Row width offset
	sbc	hl, hl
	ld	l, a
	rr	l
	jr	nc, +_
	set	PutC_OddWidth, (iy + PutC_Flags)
_:	ex	de, hl
	ld	hl, 320 / 2
	or	a
	sbc	hl, de
	ld	(iy + PutC_RowAdvance), hl
	; Loop control
	rrca
	ld	b, a
	and	3
	ld	(iy + PutC_FinalNibbles), a
	ld	a, b
	rrca
	rrca
	and	1Fh
	ld	(iy + PutC_BytesPerLine), a
	
	; ???
	
	; Font height
	ld	a, (fontHeight)
	ld	(iy + PutC_GlyphHeight), a
	; Cache colors to stack, because LEA HL, IY + simm8 is 1 bus op less than LD HL, imm24
	ld	bc, 4
	lea	de, iy + PutC_ColorsCache
	ld	hl, textColors
	ldir
	; VRAM ptr
	ld	hl, (lcdCol)
	srl	h
	rr	l
	jr	nc, +_
	set	PutC_OddStart, (iy + PutC_Flags)
_:	ld	a, (lcdRow)
	ld	e, a
	ld	d, 320 / 2
	mlt	de
	add	hl, de
	ld	de, (mpLcdBase)
	add	hl, de
	ex	de, hl
	
	bit	PutC_OddStart, (iy + PutC_Flags)
	jp	nz, PutCOddStart
PutCEvenLoop:
	ld	c, 255
	ld	a, (iy + PutC_BytesPerLine)
	or	a
	jr	z, PutCEvenFinalNibbles
	ld	b, a
_:	ld	a, (ix)
	inc	ix
	PUT_C_DO_BYTE()
	PUT_C_DO_BYTE()
	PUT_C_DO_BYTE()
	PUT_C_DO_BYTE()
	djnz	-_
PutCEvenFinalNibbles:
	ld	a, (iy + PutC_FinalNibbles)
	or	a
	ld	b, a
	jr	nz, +_
	bit	PutC_OddWidth, (iy + PutC_Flags)
	jr	z, PutCEvenNoFinalBit
	xor	a
_:	ld	a, (ix)
	inc	ix
	jr	z, PutCEvenFinalBit
_:	PUT_C_DO_BYTE()
	djnz	-_
	bit	PutC_OddWidth, (iy + PutC_Flags)
	jr	z, PutCEvenNoFinalBit
PutCEvenFinalBit:
	PUT_C_EVEN_NIBBLE()
PutCEvenNoFinalBit:
	ld	hl, (iy + PutC_RowAdvance)
	add	hl, de
	ex	de, hl
	dec	(iy + PutC_GlyphHeight)
	jp	nz, PutCEvenLoop
	jp	PutCDone
	
PutCOddStart:
PutCOddLoop:
	ld	a, (iy + PutC_BytesPerLine)
	or	a
	jr	z, PutCOddFinalNibbles
	ld	b, a
PutCOddBodyLoop:
	ld	a, (ix)
	inc	ix
	PUT_C_ODD_NIBBLE()
	inc	de
	ld	c, 255
	PUT_C_DO_BYTE()
	PUT_C_DO_BYTE()
	PUT_C_DO_BYTE()
	PUT_C_EVEN_NIBBLE()
	djnz	PutCOddBodyLoop
PutCOddFinalNibbles:
	ld	a, (iy + PutC_FinalNibbles)
	or	a
	ld	b, a
	jr	nz, +_
	bit	PutC_OddWidth, (iy + PutC_Flags)
	jr	z, PutCOddNoFinalBit
	xor	a
_:	ld	a, (ix)
	inc	ix
	jr	z, PutCOddFinalBit
_:	PUT_C_ODD_NIBBLE()
	inc	de
	PUT_C_EVEN_NIBBLE()
	djnz	-_
	bit	PutC_OddWidth, (iy + PutC_Flags)
	jr	z, PutCOddNoFinalBit
PutCOddFinalBit:
	PUT_C_ODD_NIBBLE()
PutCOddNoFinalBit:
	ld	hl, (iy + PutC_RowAdvance)
	add	hl, de
	ex	de, hl
	dec	(iy + PutC_GlyphHeight)
	jp	nz, PutCOddLoop

PutCDone:
; Update cursor
	ld	de, (lcdCol)
	or	a
	sbc	hl, hl
	ld	a, (iy + PutC_GlyphWidth)
	ld	l, a
	add	hl, de
	ld	de, 320
	sbc	hl, de
	add	hl, de
	jr	c, +_
	sbc	hl, hl
	ld	a, (fontHeight)
	ld	b, a
	ld	a, (lcdRow)
	add	a, b
	ld	(lcdRow), a
	add	a, b
	cp	240
	jr	c, +_
	xor	a
	ld	(lcdRow), a
_:	ld	(lcdCol), hl
; Close stack frame
	ld	iy, PutC_LocalsSize
	add	iy, sp
	ld	sp, iy
	pop	iy
	pop	ix
	pop	hl
	pop	de
	pop	bc
	pop	af
; End of function
	ret