134 lines
2.2 KiB
Plaintext
134 lines
2.2 KiB
Plaintext
dw DISPLAY: 0x30000
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dw stack: 0x10000
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// registers:
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// rg0 = x position
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// rg1 = y position
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// rg2 = x direction (1 = right, 0 = left)
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// rg3 = y direction (1 = down, 0 = up)
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_init:
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ldw stack, bpr
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mov bpr, spr
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start:
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lli 0, rg0
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lli 0, rg1
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lli 1, rg2
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lli 1, rg3
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frame_loop:
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// --- clear display ---
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ldw DISPLAY, rg4
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lwi 76800, rg5
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clear_loop:
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stw zero, rg4
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addi rg4, 4, rg4
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subi rg5, 1, rg5
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jnz rg5, clear_loop
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// --- draw square ---
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mov rg1, rg6
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draw_y_loop:
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lli 20, rg8
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add rg1, rg8, rg8
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ilt rg6, rg8, rg9
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jez rg9, draw_done
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mov rg0, rg7
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draw_x_loop:
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lli 20, rg8
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add rg0, rg8, rg8
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ilt rg7, rg8, rg9
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jez rg9, draw_x_done
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shl rg6, 8, rg8
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shl rg6, 6, rg9
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add rg8, rg9, rg8
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add rg8, rg7, rg8
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shl rg8, 2, rg8
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ldw DISPLAY, rg9
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add rg9, rg8, rg8
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lli 0xFFFF, rg9
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lui 0xFFFF, rg9
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stw rg9, rg8
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addi rg7, 1, rg7
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jmp draw_x_loop
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draw_x_done:
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addi rg6, 1, rg6
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jmp draw_y_loop
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draw_done:
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// --- check x walls before moving ---
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lli 1, rg8
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ieq rg2, rg8, rg9
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jez rg9, check_x_left_wall
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check_x_right_wall:
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// moving right: if x >= 300 flip direction
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lli 300, rg8
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ige rg0, rg8, rg9
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jez rg9, move_x
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lli 0, rg2
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jmp move_x
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check_x_left_wall:
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// moving left: if x == 0 flip direction
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ieq rg0, zero, rg9
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jez rg9, move_x
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lli 1, rg2
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move_x:
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lli 1, rg8
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ieq rg2, rg8, rg9
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jez rg9, do_x_left
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addi rg0, 1, rg0
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jmp check_y_walls
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do_x_left:
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subi rg0, 1, rg0
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check_y_walls:
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// --- check y walls before moving ---
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lli 1, rg8
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ieq rg3, rg8, rg9
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jez rg9, check_y_up_wall
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check_y_down_wall:
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// moving down: if y >= 220 flip direction
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lli 220, rg8
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ige rg1, rg8, rg9
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jez rg9, move_y
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lli 0, rg3
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jmp move_y
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check_y_up_wall:
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// moving up: if y == 0 flip direction
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ieq rg1, zero, rg9
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jez rg9, move_y
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lli 1, rg3
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move_y:
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lli 1, rg8
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ieq rg3, rg8, rg9
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jez rg9, do_y_up
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addi rg1, 1, rg1
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jmp delay
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do_y_up:
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subi rg1, 1, rg1
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delay:
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lwi 2000000, rg8
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delay_loop:
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subi rg8, 1, rg8
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jnz rg8, delay_loop
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jmp frame_loop
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hlt
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