diff options
Diffstat (limited to 'agbx/source/gfx/vsync.s')
| -rw-r--r-- | agbx/source/gfx/vsync.s | 21 |
1 files changed, 10 insertions, 11 deletions
diff --git a/agbx/source/gfx/vsync.s b/agbx/source/gfx/vsync.s index 5bfbe06..2e6ac3f 100644 --- a/agbx/source/gfx/vsync.s +++ b/agbx/source/gfx/vsync.s @@ -10,29 +10,28 @@ .globl agbx_vsync .func - .thumb_func agbx_vsync: @ Set the constants: - ldr r0,.scancnt @ Address of the scanline counter register. - movs r1,0xA0 @ Number of horizontal lines; + ldr r0,.vcountaddr @ agbx_i20 vcountaddr = 0x4000006u; + movs r1,0xA0 @ agbx_i20 numhline = 0xA0; .loop: @ Check the scanline counter: - ldr r2,[r0] @ Load the counter. - cmp r2,r1 @ Check if it has reached the bottom. - beq .ret @ Return if so. + ldrh r2,[r0] @ agbx_i20 vcount = *(agbx_i10 *)vcountaddr; + cmp r2,r1 + beq .ret @ if (vcount == numhline) {goto ret;} + + b .loop @ goto loop; .ret: @ Return: - bx lr + bx lr @ return; .endfunc .align -.scancnt: - .long 0x4000000 - -.align +.vcountaddr: + .long 0x4000006 |