96 lines
2.2 KiB
NASM
96 lines
2.2 KiB
NASM
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; overlay routines for window management
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; given a position on screen, find which enabled overlay (if any) is covering it
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; if multiple overlays are covering the same position, the highest priority one will be returned
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; overlay 31 (the mouse cursor) is ignored
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; inputs:
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; r0: X coordinate
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; r1: Y coordinate
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; outputs:
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; r0: overlay number, or 0xFFFFFFFF if none
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find_overlay_convering_position:
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push r2
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push r31
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mov r31, 31
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find_overlay_convering_position_loop:
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mov r2, r31
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dec r2
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call check_if_enabled_overlay_covers_position
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ifz jmp find_overlay_convering_position_found
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loop find_overlay_convering_position_loop
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; none found, return 0xFFFFFFFF
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mov r0, 0xFFFFFFFF
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pop r31
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pop r2
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ret
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find_overlay_convering_position_found:
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; found one, return its overlay number
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mov r0, r2
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pop r31
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pop r2
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ret
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; swap two overlays. this has the effect of swapping their priorities
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; this does *not* effect the enable status of either overlay
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; FIXME: this could use the stack instead
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; inputs:
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; r0: overlay number
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; r1: overlay number
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; outputs:
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; none
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swap_overlays:
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push r10
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; save first overlay
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mov r10, r0
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or r10, 0x80000000
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in [overlay_0_position], r10
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mov r10, r0
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or r10, 0x80000100
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in [overlay_0_size], r10
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mov r10, r0
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or r10, 0x80000200
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in [overlay_0_ptr], r10
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; save second overlay
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mov r10, r1
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or r10, 0x80000000
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in [overlay_1_position], r10
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mov r10, r1
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or r10, 0x80000100
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in [overlay_1_size], r10
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mov r10, r1
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or r10, 0x80000200
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in [overlay_1_ptr], r10
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; swap
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mov r10, r1
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or r10, 0x80000000
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out r10, [overlay_0_position]
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mov r10, r1
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or r10, 0x80000100
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out r10, [overlay_0_size]
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mov r10, r1
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or r10, 0x80000200
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out r10, [overlay_0_ptr]
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mov r10, r0
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or r10, 0x80000000
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out r10, [overlay_1_position]
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mov r10, r0
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or r10, 0x80000100
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out r10, [overlay_1_size]
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mov r10, r0
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or r10, 0x80000200
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out r10, [overlay_1_ptr]
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pop r10
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ret
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overlay_0_position: data.32 0x00000000
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overlay_0_size: data.32 0x00000000
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overlay_0_ptr: data.32 0x00000000
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overlay_1_position: data.32 0x00000000
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overlay_1_size: data.32 0x00000000
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overlay_1_ptr: data.32 0x00000000
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