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@ 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_getvbnk
.globl agbx_getvbnk
.func
.thumb_func
agbx_getvbnk:
@ Get the current value of dispcnt:
ldr r0,.dispcntaddr @ agbx_i20 dispcntaddr = 0x4000000u;
ldrh r1,[r0] @ agbx_i10 dispcnt = *(agbx_i10 *)dispcntaddr;
@ Get the address:
b __agbx_getvbnk @ agbx_i20 vaddr = __agbx_getvbnk();
bx lr @ return vaddr;
.endfunc
.func
.thumb_func
__agbx_getvbnk: @ Takes the value of dispcnt in r1.
@ Check if the fifth bit is set:
movs r0,0b10000
tst r1,r0
beq .vbnk1
.vbnk0:
@ Return the address of the first video bank:
ldr r0,.vbnk0addr
bx lr
.vbnk1:
@ Return the address of the second video bank:
ldr r0,.vbnk1addr
bx lr
.endfunc
.align
.dispcntaddr:
.long 0x4000000
.align
.vbnk0addr:
.long 0x6000000
.align
.vbnk1addr:
.long 0x600A000
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