Begin simplifying map API

inc/dir.inc

@@ -1,10 +0,0 @@
-DEF DIRF_UP EQU (1 << 0)
-DEF DIRF_RIGHT EQU (1 << 1)
-DEF DIRF_DOWN EQU (1 << 2)
-DEF DIRF_LEFT EQU (1 << 3)
-
-RSRESET
-DEF DIRB_UP RB 1
-DEF DIRB_RIGHT RB 1
-DEF DIRB_DOWN RB 1
-DEF DIRB_LEFT RB 1

src/main.s

@@ -1,4 +1,3 @@
-INCLUDE "dir.inc"
 INCLUDE "hardware.inc"
 INCLUDE "util.inc"
 
@@ -57,13 +56,6 @@ start:
 
     call Keys_Update
 
-    ; Clear pending map state
-    xor a
-    ld [PENDING_ROW_PTR], a
-    ld [PENDING_ROW_PTR + 1], a
-    ld [PENDING_COL_PTR], a
-    ld [PENDING_COL_PTR + 1], a
-
     call scroll_update
 
     ; wait for vblank
@@ -77,42 +69,15 @@ start:
 
     jp .loop
 
-; TODO: remove once scrolling is implemented
+; TODO: Move into player movement routine
 scroll_update:
 ; scroll map with arrow keys
     ld a, [keys]
     and PADF_UP
     jr z, .down
 
-    ; don't scroll up if on last tile
-    ld hl, rSCY
-    ld a, [hl]
-    and %111
-    jr nz, .update_up
-
-    ld hl, CURRENT_CAMERA_Y
-    ld a, [hl]
-    or a
-    ret z
-
-.update_up:
-    ld hl, rSCY
-    dec [hl]
-
-    ld a, DIRB_UP
-    ld [SCROLL_DIR], a
-
-    ld a, [hl]
-    and %111
-    cp %111
-    jr nz, .update_up_map
-
-    ld a, [CURRENT_CAMERA_Y]
-    dec a
-    ld [CURRENT_CAMERA_Y], a
-
-.update_up_map:
-    call Map_Scroll
+    ld d, 1
+    call Map_ScrollUp
     ret
 
 .down:
@@ -120,35 +85,8 @@ scroll_update:
     and PADF_DOWN
     jr z, .right
 
-    ; don't scroll down if on last tile
-    ld a, [rSCY]
-    and %111
-    jr nz, .update_down
-
-    ld a, [CURRENT_MAP_HEIGHT]
-    ld b, a
-    ld a, [CURRENT_CAMERA_Y]
-    add 18
-    cp b
-    ret z
-
-.update_down:
-    ld hl, rSCY
-    inc [hl]
-
-    ld a, DIRB_DOWN
-    ld [SCROLL_DIR], a
-
-    ld a, [hl]
-    and %111
-    jr nz, .update_down_map
-
-    ld a, [CURRENT_CAMERA_Y]
-    inc a
-    ld [CURRENT_CAMERA_Y], a
-
-.update_down_map:
-    call Map_Scroll
+    ld d, 1
+    call Map_ScrollDown
     ret
 
 .right:
@@ -156,36 +94,8 @@ scroll_update:
     and PADF_RIGHT
     jr z, .left
 
-    ; don't scroll right if on last tile
-    ld hl, rSCX
-    ld a, [hl]
-    and %111
-    jr nz, .update_right
-
-    ld a, [CURRENT_MAP_WIDTH]
-    ld b, a
-    ld a, [CURRENT_CAMERA_X]
-    add SCRN_X_B
-    cp b
-    ret z
-
-.update_right:
-    ld hl, rSCX
-    inc [hl]
-
-    ld a, DIRB_RIGHT
-    ld [SCROLL_DIR], a
-
-    ld a, [hl]
-    and %111
-    jr nz, .update_right_map
-
-    ld a, [CURRENT_CAMERA_X]
-    inc a
-    ld [CURRENT_CAMERA_X], a
-
-.update_right_map:
-    call Map_Scroll
+    ld d, 1
+    call Map_ScrollRight
     ret
 
 .left:
@@ -193,33 +103,5 @@ scroll_update:
     and PADF_LEFT
     ret z
 
-    ; don't scroll left if on last tile
-    ld hl, rSCX
-    ld a, [hl]
-    and %111
-    jr nz, .update_left
-
-    ld hl, CURRENT_CAMERA_X
-    ld a, [hl]
-    or a
-    ret z
-
-.update_left:
-    ld hl, rSCX
-    dec [hl]
-
-    ld a, DIRB_LEFT
-    ld [SCROLL_DIR], a
-
-    ld a, [hl]
-    and %111
-    cp %111
-    jr nz, .update_left_map
-
-    ld a, [CURRENT_CAMERA_X]
-    dec a
-    ld [CURRENT_CAMERA_X], a
-
-.update_left_map:
-    call Map_Scroll
-    ret
+    ld d, 1
+    call Map_ScrollLeft

src/map.s

@@ -1,4 +1,3 @@
-INCLUDE "dir.inc"
 INCLUDE "hardware.inc"
 INCLUDE "util.inc"
 
@@ -7,8 +6,6 @@ SECTION "Map Data", WRAM0
 DEF ROW_BUFFER_SIZE EQUS "SCRN_X_B + 4"
 DEF COL_BUFFER_SIZE EQUS "SCRN_Y_B + 4"
 
-SCROLL_DIR:: DB
-
 PENDING_ROW_PTR:: DW ; Where to write pending row data (0 = no write)
 PENDING_ROW_DATA:: DS ROW_BUFFER_SIZE ; Row to be written
 
@@ -33,6 +30,8 @@ SECTION "Map Code", ROM0
 DEF INIT_SCX EQUS "((SCRN_VX - SCRN_X) / 2)"
 DEF INIT_SCY EQUS "((SCRN_VY - SCRN_Y) / 2)"
 
+
+
 ; Loads a map
 ; @param hl Pointer to map metadata
 Map_Load::
@@ -85,27 +84,35 @@ Map_Load::
 
     ret
 
-; Update map state based on SCX/SCY
-Map_Scroll::
-    ; Check scroll up/down
-    ld a, [SCROLL_DIR]
-    and DIRF_UP | DIRF_DOWN
-    jr nz, .scroll_horiz
 
-    ; Check SCY % 8 = 0
+
+; Scroll the map upwards
+; @param d The amount to scroll by (0 < d < 8)
+Map_ScrollUp::
+    ; Check whether we crossed tile boundary
     ld a, [rSCY]
     and %111
-    ret nz
+    cp d
+    jr nc, .done
+
+    ; Don't scroll if at top tile
+    ld a, [CURRENT_CAMERA_Y]
+    or a
+    ret z
+
+    ld a, [rSCY]
+    sub d
+    ld [rSCY], a
+
+    ; CAMERA_Y -= 1
+    dec a
+    ld [CURRENT_CAMERA_Y], a
 
     ; B = CAMERA_X - 2
     ld a, [CURRENT_CAMERA_X]
     sub 2
     ld b, a
 
-    ld a, [SCROLL_DIR]
-    cp DIRB_UP
-    jr nz, .scroll_down
-
     ; C = CAMERA_Y - 2
     ld a, [CURRENT_CAMERA_Y]
     sub 2
@@ -116,9 +123,65 @@ Map_Scroll::
     srln a, 3
     sub 2
 
-    jr .write_row
+    jr Map_ScrollRow
+
+.done:
+    ld a, [rSCY]
+    sub d
+    ld [rSCY], a
+    ret
+
+
+
+Map_ScrollDown::
+    ; Don't scroll if at bottom tile
+    ld a, [CURRENT_CAMERA_Y]
+    add SCRN_Y_B
+    ld hl, CURRENT_MAP_HEIGHT
+    cp [hl]
+    jr nz, .down
+
+    ld a, [rSCY]
+    add d
+    and %111
+    ld [rSCY], a
+    ret
+
+    ; Check whether we crossed tile boundary
+.down:
+    ld a, [rSCY]
+    and %111
+    add d
+    cp 8
+    jr c, .done
+
+    ; TODO:
+    ; if CAMERA_Y + 18 = MAP_HEIGHT {
+    ;     if SCY % 8 != 0 {
+    ;         SCY += MIN(D, 8 - SCY % 8)
+    ;     }
+    ;     return
+    ; }
+    ; if SCY % 8 + D > 8 {
+    ;     SCY += D
+    ;     LOAD_COLUMN(CAMERA_X - 2, CAMERA_Y + 18 + 1);
+    ; } else {
+    ;     SCY += D
+    ; }
+
+    ld a, [rSCY]
+    add d
+    ld [rSCY], a
+
+    ; CAMERA_Y += 1
+    inc a
+    ld [CURRENT_CAMERA_Y], a
+
+    ; B = CAMERA_X - 2
+    ld a, [CURRENT_CAMERA_X]
+    sub 2
+    ld b, a
 
-.scroll_down:
     ; C = CAMERA_Y + 18 + 1
     ld a, [CURRENT_CAMERA_Y]
     add SCRN_Y_B + 1
@@ -129,7 +192,21 @@ Map_Scroll::
     srln a, 3
     add SCRN_Y_B + 1
 
-.write_row:
+    jr Map_ScrollRow
+
+.done:
+    ld a, [rSCY]
+    add d
+    ld [rSCY], a
+    ret
+
+
+
+; Scroll in a new row
+; @param a Map VRAM Y-coordinate
+; @param b Data X-coordinate
+; @param c Data Y-coordinate
+Map_ScrollRow:
     and %11111
     call get_row_ptr
 
@@ -145,16 +222,21 @@ Map_Scroll::
     call enqueue_row_write
     ret
 
-.scroll_horiz:
-    ; Check SCX % 8 = 0
+Map_ScrollLeft::
+    ; Check whether we crossed tile boundary
     ld a, [rSCX]
     and %111
-    ret nz
+    cp d
+    jr nc, .done
 
-    ; C = CAMERA_Y - 2
-    ld a, [CURRENT_CAMERA_Y]
-    sub 2
-    ld c, a
+    ld a, [rSCX]
+    sub d
+    ld [rSCX], a
+
+    ; Don't scroll if at left tile
+    ld a, [CURRENT_CAMERA_X]
+    or a
+    ret z
 
     ld a, [rSCY]
     sub 16
@@ -163,42 +245,91 @@ Map_Scroll::
     srl a
     call get_row_ptr
 
-    ld a, [SCROLL_DIR]
-    cp DIRB_LEFT
-    jr nz, .scroll_right
-
     ; B = CAMERA_X - 2
     ld a, [CURRENT_CAMERA_X]
     sub 2
     ld b, a
 
-    ; HL = VRAM + (SCX/8 - 2)
+    ; E = VRAM + (SCX/8 - 2)
     ld a, [rSCX]
     srln a, 3
     sub 2
 
-    jr .write_col
+    jr Map_ScrollColumn
+
+.done:
+    ld a, [rSCX]
+    sub d
+    ld [rSCX], a
+    ret
+
+
+
+Map_ScrollRight::
+    ; Check whether we crossed tile boundary
+    ld a, [rSCX]
+    and %111
+    add d
+    cp 8
+    jr nc, .done
+
+    ld a, [rSCX]
+    add d
+    ld [rSCX], a
+
+    ; Don't scroll if at bottom tile
+    ld a, [CURRENT_CAMERA_X]
+    inc a
+    ld hl, CURRENT_MAP_WIDTH
+    cp [hl]
+    ret z
+
+    ; CAMERA_X += 1
+    inc a
+    ld [CURRENT_CAMERA_X], a
+
+    ld a, [rSCY]
+    sub 16
+    srl a
+    srl a
+    srl a
+    call get_row_ptr
 
-.scroll_right:
     ; B = CAMERA_X + 20 + 1
     ld a, [CURRENT_CAMERA_X]
     add SCRN_X_B + 1
     ld b, a
 
-    ; HL = VRAM + SCX/8 + SCRN_X_B + 1
+    ; E = VRAM + SCX/8 + SCRN_X_B + 1
     ld a, [rSCX]
     srl a
     srl a
     srl a
     add SCRN_X_B + 1
+    ld e, a
 
-.write_col:
-    and %11111
-    ADD16 hl
+    jr Map_ScrollColumn
+
+.done:
+    ld a, [rSCX]
+    add d
+    ld [rSCX], a
+    ret
+
+
+
+Map_ScrollColumn:
+    ; C = CAMERA_Y - 2
+    ld a, [CURRENT_CAMERA_Y]
+    sub 2
+    ld c, a
 
     call enqueue_col_write
     ret
 
+
+
+
 Map_Update::
     ; Skip row update if PENDING_ROW_PTR is 0
     ld a, [PENDING_ROW_PTR]
@@ -232,6 +363,11 @@ Map_Update::
     dec d
     jr nz, .copy_row
 
+    ; Reset PENDING_ROW_PTR
+    xor a
+    ld [PENDING_ROW_PTR], a
+    ld [PENDING_ROW_PTR + 1], a
+
 .update_col:
     ; Skip column update if PENDING_COL_PTR is 0
     ld a, [PENDING_COL_PTR]
@@ -259,8 +395,15 @@ Map_Update::
     dec d
     jr nz, .update_col_loop
 
+    ; Reset PENDING_COL_PTR
+    xor a
+    ld [PENDING_COL_PTR], a
+    ld [PENDING_COL_PTR + 1], a
+
     ret
 
+
+
 ; Computes the offset into map RAM
 ; @param a The map RAM y-coordinate
 ; @return hl Pointer into map RAM
@@ -276,6 +419,8 @@ get_row_ptr:
     pop de
     ret
 
+
+
 ; Write a row of map data into row buffer
 ; @param b Map X coordinate (signed)
 ; @param c Map Y coordinate (signed)
@@ -398,6 +543,8 @@ enqueue_row_write:
     jr nz, .zero_row_loop
     ret
 
+
+
 ; NOTE: This works by enqueueing a row to write, and then immediately flushing
 ; the queue. The subroutine could be sped up by writing to map RAM directly, but
 ; this is simpler to write and saves on code size.
@@ -419,6 +566,8 @@ write_map_row:
 
     ret
 
+
+
 ; Write a column of map data into column buffer
 ; @param b Map X coordinate (signed)
 ; @param c Map Y coordinate (signed)
@@ -545,6 +694,7 @@ enqueue_col_write:
     ret
 
 
+
 ; Basically enqueue_col_write but for entire row, used during map load
 ; TODO: Deduplicate
 ; @param b Map X coordinate (signed)