Hi,
I looked for a while and couldn't find anything on this, so could
someone help me? I'm trying to make a hw-compatible game, and its
going to be done using mode 4 graphics. I know that you have to do
16bit writes to VRAM, so I made a little read-modify-write PlotPixel
function. It looks like this:

void PixelOn(u8 x, u8 y, u8 c)
{
u16 *p;

p = &VBUFFER16[((y<<8)-(y<<4)+x)>>1];

*p = (x & 1 ? (*p & 0xFF00) | c : (*p & 0x00FF) | (c << 8));
}

It gets compiled right, there arent any weird optimizations. After I
optimized 2 little stupid lines out, this is the ASM:

void PixelOn(u8 x, u8 y, u8 c) //a1 = x , a2 = y, a3 = color
{
__asm
{
MOV a4,a2,LSL #8
SUB a2,a4,a2,LSL #4
ADD a2,a2,a1
MOV a4,#0x6000000
ADD a2,a4,a2
TST a1,#1
LDRH a1,[a2,#0]
ANDNE a1,a1,#0x00ff
ORRNE a1,a1,a3,LSL #8
ANDEQ a1,a1,#0xff00
ORREQ a1,a1,a3
STRH a1,[a2,#0]
}
}

I know it is in ARM, and I don't care for now. The real question is
why this doesn't work on any emulator but Mappy and VGBA (I'm using
0.6)? I'm thinking its an emulator bug. Could someone test my
function on real hardware?

Thanks

Rattboi