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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 ax_vsync
.func
.thumb_func
ax_vsync:
@ Set the constants:
ldr r0,.vcntaddr @ ax_i02 vcntaddr = 0x4000006u;
.waitvdrw: @ waitvdrw:;
@ Wait for the next VDraw:
ldrh r2,[r0] @ ax_i02 vcnt = *(ax_i01 *)vcntaddr;
cmp r2,0x0
beq .waitvblnk @ if (vcnt == 0x0u) goto waitvblnk;
b .waitvdrw @ goto waitvdrw;
.waitvblnk: @ waitvblnk:;
@ Wait for the VBlank:
ldrh r2,[r0] @ ax_i02 vcnt = *(ax_i01 *)vcntaddr;
cmp r2,0xA0
beq .ret @ if (vcnt == 0xA0u) goto ret;
b .waitvblnk @ goto waitvblnk;
.ret:
@ Return:
bx lr @ return;
.endfunc
.align
.vcntaddr:
.word 0x4000006
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