git.y1.nz

commit 0fa82be14d6e9bb7c02211dba42e9134cfca3fa7
parent 6a41699223e8728a74d9564fee5a3c3bf79abbfb
Author: toxa <untoxa@mail.ru>
Date:   Sun, 11 Oct 2020 21:48:53 +0300

functions for loading 1bpp tile data

Diffstat:
M
gbdk-lib/include/gb/gb.h
12
++++++++++++
M
gbdk-lib/libc/gb/Makefile
1
+
A
gbdk-lib/libc/gb/set_1bit_data.s
81
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 94 insertions(+), 0 deletions(-)
diff --git a/gbdk-lib/include/gb/gb.h b/gbdk-lib/include/gb/gb.h
@@ -454,6 +454,10 @@ void set_bkg_data(UINT8 first_tile,
          UINT8 nb_tiles,
          unsigned char *data) NONBANKED __preserves_regs(b, c);
 
+void set_bkg_1bit_data(UINT8 first_tile,
+         UINT8 nb_tiles,
+         unsigned char *data) NONBANKED __preserves_regs(b, c);
+
 void get_bkg_data(UINT8 first_tile,
          UINT8 nb_tiles,
          unsigned char *data) NONBANKED __preserves_regs(b, c);
@@ -513,6 +517,10 @@ void set_win_data(UINT8 first_tile,
           UINT8 nb_tiles,
           unsigned char *data) NONBANKED __preserves_regs(b, c);
 
+void set_win_1bit_data(UINT8 first_tile,
+          UINT8 nb_tiles,
+          unsigned char *data) NONBANKED __preserves_regs(b, c);
+
 void get_win_data(UINT8 first_tile,
           UINT8 nb_tiles,
           unsigned char *data) NONBANKED __preserves_regs(b, c);
@@ -592,6 +600,10 @@ void set_sprite_data(UINT8 first_tile,
           UINT8 nb_tiles,
           unsigned char *data) NONBANKED __preserves_regs(b, c);
 
+void set_sprite_1bit_data(UINT8 first_tile,
+          UINT8 nb_tiles,
+          unsigned char *data) NONBANKED __preserves_regs(b, c);
+
 void get_sprite_data(UINT8 first_tile,
           UINT8 nb_tiles,
           unsigned char *data) NONBANKED __preserves_regs(b, c);
diff --git a/gbdk-lib/libc/gb/Makefile b/gbdk-lib/libc/gb/Makefile
@@ -14,6 +14,7 @@ ASSRC =	cgb.s cpy_data.s drawing.s f_ibm_sh.s \
 	pad.s sample.s \
 	serial.s set_bk_t.s \
 	set_data.s set_prop.s set_spr.s set_wi_t.s set_xy_t.s \
+	set_1bit_data.s \
 	sgb.s font.s delay.s \
 	rand.s arand.s \
 	bgb_emu.s \
diff --git a/gbdk-lib/libc/gb/set_1bit_data.s b/gbdk-lib/libc/gb/set_1bit_data.s
@@ -0,0 +1,80 @@
+	.include	"global.s"
+
+	.globl	.copy_vram
+
+	.area	_BASE
+
+.macro WAIT_STAT ?lbl
+lbl:	ldh a, (.STAT)
+	and #2 ; Check if in LCD modes 0 or 1
+	jr nz, lbl
+.endm
+
+_set_bkg_1bit_data::
+_set_win_1bit_data::
+	ld d, #0x90
+	ldh a, (.LCDC)
+	bit 4, a
+	jr z, .copy_1bit_tiles
+_set_sprite_1bit_data::
+	ld d, #0x80
+.copy_1bit_tiles:
+	push bc
+	lda hl, 4(sp)
+	ld a, (hl+) ; ID of 1st tile
+	ld e, a
+	ld a, (hl+) ; Nb of tiles
+	ld c, a
+	ld a, (hl+) ; Src ptr
+	ld h, (hl)
+	ld l, a
+	
+	; Compute dest ptr
+	swap e ; *16 (size of a tile)
+	ld a, e
+	and #0x0F ; Get high bits
+	add a, d ; Add base offset of target tile "block"
+	ld d, a
+	ld a, e
+	and #0xF0 ; Get low bits only
+	ld e, a
+	
+1$:
+	; Wrap from past $97FF to $8800 onwards
+	; This can be reduced to "bit 4 must be clear if bit 3 is set"
+	bit 3, d
+	jr z, 2$
+	res 4, d
+2$:	
+	.rept 3		; Repeat this 4 more times to copy 16 bytes...
+		WAIT_STAT
+		; We have 16 cycles free to access VRAM, during which we can copy 3 bytes
+		ld a, (hl+)
+		ld (de), a
+		inc e ; inc de
+		ld (de), a
+		inc e ; inc de
+		ld a, (hl+)
+		ld (de), a
+		inc e ; inc de
+		ld (de), a
+		inc e ; inc de
+	.endm
+	WAIT_STAT
+	; We have 16 cycles free to access VRAM, during which we can copy 3 bytes
+	ld a, (hl+)
+	ld (de), a
+	inc e ; inc de
+	ld (de), a
+	inc e ; inc de
+	ld a, (hl+)
+	ld (de), a
+	inc e ; inc de
+	ld (de), a
+	inc de ; This actually can overflow into the high byte
+
+	dec c
+	jr nz, 1$
+	
+	pop bc
+	ret
+

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