From 21968ae8ef0dab16319c41277007f3abd1b0285b Mon Sep 17 00:00:00 2001
From: greg <elorian.mestec@gmail.com>
Date: Thu, 15 Dec 2016 00:01:32 -0800
Subject: [PATCH] DMA write to tile map

DMA write was always working, I just had the wrong tile data format
Tile data is two bytes, not wrong

Also keep around previously-working tile-load loop for prosterity
---
 my_custom.asm | 26 +++++++++++++++++++++
 test_gfx.asm  | 65 +++++++++++++++++++++++++++------------------------
 2 files changed, 61 insertions(+), 30 deletions(-)

diff --git a/my_custom.asm b/my_custom.asm
index ac2a7b9..2ee9b3f 100644
--- a/my_custom.asm
+++ b/my_custom.asm
@@ -45,3 +45,29 @@ lda #\1
 sta $2100 ; $2100 is the screen brightness register
 
 .ENDM
+
+
+
+; loads, in a loop, an alternating grid of tiles
+.MACRO Tile_Load_Loop
+
+    ldx #$0400 ; load $0400 (VRAM address of tile data)
+TileLoadLoop:
+
+    stx $2116  ; store VRAM address of tile data to VRAM address word-sized register
+
+    lda #$01   ; smile tile
+    sta $2118  ;store tile map entry to the address specified in $2116 - this increments or not based on 2115
+
+    inx
+    stx $2116
+
+    lda #$00 ; blank tile
+    sta $2118
+
+    inx
+
+    cpx #$0780 ; $400 - $780 seems to be limit of snes screen tile memory
+    bne TileLoadLoop
+
+.ENDM
diff --git a/test_gfx.asm b/test_gfx.asm
index 6a783a1..7e2d326 100644
--- a/test_gfx.asm
+++ b/test_gfx.asm
@@ -36,7 +36,7 @@ VBlank:
     sta $4304 ; store bank into DMA source bank
     sty $4305 ; store size of block
 
-    lda #$01  
+    lda #$01
     sta $4300  ; set DMA mode (word, normal increment)
 
     lda #$18
@@ -77,27 +77,9 @@ Start:
     lda #%00000001
     sta $212c ; enable bkg 1,
 
-;    Load_Block_to_VRAM TileMap, $0400, 16
-    Load_Block_to_VRAM Tiles, $0000, (8*2*2),
+    Load_Block_to_VRAM Tiles, $0000, (8*2*3),
 
-    ldx #$0400 ; load $0400 (VRAM address of tile data)
-TileLoadLoop:
-
-    stx $2116  ; store VRAM address of tile data to VRAM address word-sized register
-
-    lda #$01   ; smile tile
-    sta $2118  ;store tile map entry to the address specified in $2116 - this increments or not based on 2115
-
-    inx
-    stx $2116
-
-    lda #$00 ; blank tile
-    sta $2118
-
-    inx
-
-    cpx #$0780 ; $400 - $780 seems to be limit of snes screen tile memory
-    bne TileLoadLoop
+    Load_Block_to_VRAM TileMap, $0400, 4
 
 lda #%10000001  ; enable NMI and joypads
 sta $4200
@@ -159,14 +141,37 @@ Tiles:
     .db %00111100
     .db %00111100
 
-TileMap:
-    .db $00, $01
-    .db $00, $01
-    .db $00, $01
-    .db $00, $01
-    .db $00, $01
-    .db $00, $01
-    .db $00, $01
-    .db $00, $01
+; different face
+    .db %11111111
+    .db %00000000
 
+    .db %11111111
+    .db %00000000
+
+    .db %11000011
+    .db %00000000
+
+    .db %00111000
+    .db %00111000
+
+    .db %00111000
+    .db %00111000
+
+    .db %10000001
+    .db %10000001
+
+    .db %01000010
+    .db %01000010
+
+    .db %00111100
+    .db %00111100
+
+
+; each entry in the tile map is two bytes long
+; here is the format:
+;High        Low                 v: vertical flip    h: horizontal flip
+;vhopppcc    cccccccc            o: priority bit     p: palette number
+;                                c: Starting character (tile) number
+TileMap:
+    .db $02, $00, $02, $00
 .ENDS