static status_t
GetEdidFromBIOS(edid1_raw& edidRaw)
{
// Get the EDID info from the video BIOS, and return B_OK if successful.
#define ADDRESS_SEGMENT(address) ((addr_t)(address) >> 4)
#define ADDRESS_OFFSET(address) ((addr_t)(address) & 0xf)
vm86_state vmState;
status_t status = vm86_prepare(&vmState, 0x2000);
if (status != B_OK) {
TRACE("GetEdidFromBIOS(); vm86_prepare() failed, status: 0x%lx\n",
status);
return status;
}
vmState.regs.eax = 0x4f15;
vmState.regs.ebx = 0; // 0 = report DDC service
vmState.regs.ecx = 0;
vmState.regs.es = 0;
vmState.regs.edi = 0;
status = vm86_do_int(&vmState, 0x10);
if (status == B_OK) {
// AH contains the error code, and AL determines wether or not the
// function is supported.
if (vmState.regs.eax != 0x4f)
status = B_NOT_SUPPORTED;
// Test if DDC is supported by the monitor.
if ((vmState.regs.ebx & 3) == 0)
status = B_NOT_SUPPORTED;
}
if (status == B_OK) {
// According to the author of the vm86 functions, the address of any
// object to receive data must be >= 0x1000 and within the ram size
// specified in the second argument of the vm86_prepare() call above.
// Thus, the address of the struct to receive the EDID info is set to
// 0x1000.
edid1_raw* edid = (edid1_raw*)0x1000;
vmState.regs.eax = 0x4f15;
vmState.regs.ebx = 1; // 1 = read EDID
vmState.regs.ecx = 0;
vmState.regs.edx = 0;
vmState.regs.es = ADDRESS_SEGMENT(edid);
vmState.regs.edi = ADDRESS_OFFSET(edid);
status = vm86_do_int(&vmState, 0x10);
if (status == B_OK) {
if (vmState.regs.eax != 0x4f) {
status = B_NOT_SUPPORTED;
} else {
// Copy the EDID info to the caller's location, and compute the
// checksum of the EDID info while copying.
uint8 sum = 0;
uint8 allOr = 0;
uint8* dest = (uint8*)&edidRaw;
uint8* src = (uint8*)edid;
for (uint32 j = 0; j < sizeof(edidRaw); j++) {
sum += *src;
allOr |= *src;
*dest++ = *src++;
}
if (allOr == 0) {
TRACE("GetEdidFromBIOS(); EDID info contains only zeros\n");
status = B_ERROR;
} else if (sum != 0) {
TRACE("GetEdidFromBIOS(); Checksum error in EDID info\n");
status = B_ERROR;
}
}
}
}
vm86_cleanup(&vmState);
return status;
}
static status_t
GetEdidFromBIOS(edid1_raw& edidRaw)
{
// Get the EDID info from the video BIOS, and return B_OK if successful.
#define ADDRESS_SEGMENT(address) ((addr_t)(address) >> 4)
#define ADDRESS_OFFSET(address) ((addr_t)(address) & 0xf)
bios_module_info* biosModule;
status_t status = get_module(B_BIOS_MODULE_NAME, (module_info**)&biosModule);
if (status != B_OK) {
TRACE("GetEdidFromBIOS(): failed to get BIOS module: 0x%" B_PRIx32 "\n",
status);
return status;
}
bios_state* state;
status = biosModule->prepare(&state);
if (status != B_OK) {
TRACE("GetEdidFromBIOS(): bios_prepare() failed: 0x%" B_PRIx32 "\n",
status);
put_module(B_BIOS_MODULE_NAME);
return status;
}
bios_regs regs = {};
regs.eax = 0x4f15;
regs.ebx = 0; // 0 = report DDC service
regs.ecx = 0;
regs.es = 0;
regs.edi = 0;
status = biosModule->interrupt(state, 0x10, ®s);
if (status == B_OK) {
// AH contains the error code, and AL determines whether or not the
// function is supported.
if (regs.eax != 0x4f)
status = B_NOT_SUPPORTED;
// Test if DDC is supported by the monitor.
if ((regs.ebx & 3) == 0)
status = B_NOT_SUPPORTED;
}
if (status == B_OK) {
edid1_raw* edid = (edid1_raw*)biosModule->allocate_mem(state,
sizeof(edid1_raw));
if (edid == NULL) {
status = B_NO_MEMORY;
goto out;
}
regs.eax = 0x4f15;
regs.ebx = 1; // 1 = read EDID
regs.ecx = 0;
regs.edx = 0;
regs.es = ADDRESS_SEGMENT(edid);
regs.edi = ADDRESS_OFFSET(edid);
status = biosModule->interrupt(state, 0x10, ®s);
if (status == B_OK) {
if (regs.eax != 0x4f) {
status = B_NOT_SUPPORTED;
} else {
// Copy the EDID info to the caller's location, and compute the
// checksum of the EDID info while copying.
uint8 sum = 0;
uint8 allOr = 0;
uint8* dest = (uint8*)&edidRaw;
uint8* src = (uint8*)edid;
for (uint32 j = 0; j < sizeof(edidRaw); j++) {
sum += *src;
allOr |= *src;
*dest++ = *src++;
}
if (allOr == 0) {
TRACE("GetEdidFromBIOS(); EDID info contains only zeros\n");
status = B_ERROR;
} else if (sum != 0) {
TRACE("GetEdidFromBIOS(); Checksum error in EDID info\n");
status = B_ERROR;
}
}
}
}
out:
biosModule->finish(state);
put_module(B_BIOS_MODULE_NAME);
TRACE("GetEdidFromBIOS() status: 0x%" B_PRIx32 "\n", status);
return status;
}
