diff options
Diffstat (limited to 'agbx/source/gfx/flip.s')
| -rw-r--r-- | agbx/source/gfx/flip.s | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/agbx/source/gfx/flip.s b/agbx/source/gfx/flip.s new file mode 100644 index 0000000..c2f4336 --- /dev/null +++ b/agbx/source/gfx/flip.s @@ -0,0 +1,47 @@ +@ Copyright 2022 Gabriel Jensen. +@ This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. +@ If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/. + +.syntax unified + +.cpu arm7tdmi +.thumb + +.globl agbx_flip + +.func + +.thumb_func + +agbx_flip: + ldr r0,.dispcntaddr + ldrh r1,[r0] @ Get the current value of dispcnt. + movs r2,#0b10000 + eors r1,r2 @ XOR bit five. + strh r1,[r0] @ Save dispcnt. + movs r0,#0x10 + tst r1,r0 @ Check what video bank we should return the address of. + beq .vbnk0 +.vbnk1: + ldr r0,.vbnk1addr + bx lr +.vbnk0: + ldr r0,.vbnk0addr + bx lr + +.endfunc + +.align + +.dispcntaddr: + .long 0x4000000 + +.align + +.vbnk0addr: + .long 0x6000000 + +.align + +.vbnk1addr: + .long 0x600A000 |