replace texture jump table with dispatch table

(cherry picked from commit 88f10f9f06)

build.ts

@@ -10,6 +10,7 @@ if (Deno.args.length !== 0) {
 import { TextLineStream } from "jsr:@std/streams@1.1.0";
 
 const asmFilePaths = [
+  "src/consts/arch.asm",
   "src/consts/game.asm",
   "src/consts/keyboard.asm",
   "src/consts/map.asm",
@@ -17,6 +18,7 @@ const asmFilePaths = [
   "src/consts/screen.asm",
   "src/consts/sprites.asm",
 
+  "src/init.asm",
   "src/main.asm",
 
   "src/lib/game.asm",

src/consts/arch.asm

@@ -0,0 +1,2 @@
+pub const arch.instruction_size = 4
+pub const arch.instruction_increment_shift = 2

src/init.asm

@@ -0,0 +1,70 @@
+;
+;   Jump table initialisation
+;
+; r1: sprite id
+; r2: pointer address
+; r3: pointer value
+
+; sprite_empty
+add r1, zr, sprites.empty
+lsl r2, r1, arch.instruction_increment_shift
+add r2, r2, ptr.textures_addresses
+add r3, zr, sprite_empty
+store_32 [r2], r3
+; sprite_unimplemented
+add r1, zr, sprites.unimplemented
+lsl r2, r1, arch.instruction_increment_shift
+add r2, r2, ptr.textures_addresses
+add r3, zr, sprite_unimplemented
+store_32 [r2], r3
+; sprite_wall_end
+add r1, zr, sprites.wall_end
+lsl r2, r1, arch.instruction_increment_shift
+add r2, r2, ptr.textures_addresses
+add r3, zr, sprite_wall_end
+store_32 [r2], r3
+; sprite_wall_straight
+add r1, zr, sprites.wall_straight
+lsl r2, r1, arch.instruction_increment_shift
+add r2, r2, ptr.textures_addresses
+add r3, zr, sprite_wall_straight
+store_32 [r2], r3
+; sprite_wall_corner
+add r1, zr, sprites.wall_corner
+lsl r2, r1, arch.instruction_increment_shift
+add r2, r2, ptr.textures_addresses
+add r3, zr, sprite_wall_corner
+store_32 [r2], r3
+; sprite_robot
+add r1, zr, sprites.robot
+lsl r2, r1, arch.instruction_increment_shift
+add r2, r2, ptr.textures_addresses
+add r3, zr, sprite_robot
+store_32 [r2], r3
+; sprite_ghost
+add r1, zr, sprites.ghost
+lsl r2, r1, arch.instruction_increment_shift
+add r2, r2, ptr.textures_addresses
+add r3, zr, sprite_ghost
+store_32 [r2], r3
+; sprite_coin
+add r1, zr, sprites.coin
+lsl r2, r1, arch.instruction_increment_shift
+add r2, r2, ptr.textures_addresses
+add r3, zr, sprite_coin
+store_32 [r2], r3
+
+;
+;   Screen initialization
+;
+
+; r1 = screen parameter value
+mov r1, screen.mode_index
+screen r1, screen.mode_value
+
+mov r1, screen.offset_index
+add r2, zr, ptr.screen
+screen r1, r2
+
+mov r1, screen.resolution_index
+screen r1, screen.resolution_value

src/lib/drawing.asm

@@ -120,48 +120,21 @@ get_tile_address:
 ; 	r13: address
 
 ; Locals:
-;		r2: jump address
+;		r2: pointer address
 ; */
 get_sprite_address:
 	push r1
 	push r2
 
 	cmp r1, sprites.max
-	jbe get_sprite_address_jmp_table_init
+	jbe get_sprite_address_ptr
 	mov r1, sprites.unimplemented
 
-	get_sprite_address_jmp_table_init:
+	get_sprite_address_ptr:
-	lsl r2, r1, 3 ; 2*instruction_size = *8 = <<3
+	lsl r2, r1, arch.instruction_increment_shift
-	add r2, r2, get_sprite_address_jmp_table_start
+	add r2, r2, ptr.textures_addresses
-	jmp r2
+	load_32 r13, [r2]
 
-	get_sprite_address_jmp_table_start:
-	; sprite_empty
-	add r13, zr, sprite_empty
-	jmp get_sprite_address_return
-	; sprite_unimplemented:
-	add r13, zr, sprite_unimplemented
-	jmp get_sprite_address_return
-	; sprite_wall_end
-	add r13, zr, sprite_wall_end
-	jmp get_sprite_address_return
-	; sprite_wall_straight
-	add r13, zr, sprite_wall_straight
-	jmp get_sprite_address_return
-	; sprite_wall_corner
-	add r13, zr, sprite_wall_corner
-	jmp get_sprite_address_return
-	; sprite_robot
-	add r13, zr, sprite_robot
-	jmp get_sprite_address_return
-	; sprite_ghost
-	add r13, zr, sprite_ghost
-	jmp get_sprite_address_return
-	; sprite_coin:
-	add r13, zr, sprite_coin
-	;jmp get_sprite_address_return
-
-	get_sprite_address_return:
 	pop r2
 	pop r1
 	ret

src/main.asm

@@ -1,19 +1,6 @@
 include consts/screen
 
-;
+include init
-;   Screen initialization
-;
-
-; r1 = screen parameter value
-mov r1, screen.mode_index
-screen r1, screen.mode_value
-
-mov r1, screen.offset_index
-add r2, zr, ptr.screen
-screen r1, r2
-
-mov r1, screen.resolution_index
-screen r1, screen.resolution_value
 
 call drawing.draw_whole_map
 

src/reserved_space.asm

@@ -1,3 +1,14 @@
+; Sprite addresses jump table
+pub ptr.textures_addresses:
+U32 0 ; empty
+U32 0 ; placeholder
+U32 0 ; wall_end
+U32 0 ; wall_straight
+U32 0 ; wall_corner
+U32 0 ; robot
+U32 0 ; ghost
+U32 0 ; coin
+
 ; 0.5 second = 500_000_000 nano second = 0x0000_0000_1DCD_6500
 pub ptr.tick_duration_high: U32 0x0000_0000
 pub ptr.tick_duration_low:  U32 0x1DCD_6500