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86Box/src/video/vid_ddc.c
OBattler 77cb4e6c79 Fixed DDC manufacturer.
2020-11-18 04:25:38 +01:00

335 lines
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#include <stdio.h>
#include <stdint.h>
#include <string.h>
/*
* 86Box A hypervisor and IBM PC system emulator that specializes in
* running old operating systems and software designed for IBM
* PC systems and compatibles from 1981 through fairly recent
* system designs based on the PCI bus.
*
* This file is part of the 86Box distribution.
*
* DDC monitor emulation.
*
*
*
* Authors: Sarah Walker, <http://pcem-emulator.co.uk/>
*
* Copyright 2008-2020 Sarah Walker.
*/
#include <stdlib.h>
#include <stddef.h>
#include <wchar.h>
#include <math.h>
#include <86box/86box.h>
#include "cpu.h"
#include <86box/vid_ddc.h>
static uint8_t edid_data[128] =
{
0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00, /*Fixed header pattern*/
0x09, 0xf8, /*Manufacturer "BOX" - apparently unassigned by UEFI - and it has to be big endian*/
0x00, 0x00, /*Product code*/
0x12, 0x34, 0x56, 0x78, /*Serial number*/
0x01, 9, /*Manufacturer week and year*/
0x01, 0x03, /*EDID version (1.3)*/
0x08, /*Analogue input, separate sync*/
34, 0, /*Landscape, 4:3*/
0, /*Gamma*/
0x08, /*RGB colour*/
0x81, 0xf1, 0xa3, 0x57, 0x53, 0x9f, 0x27, 0x0a, 0x50, /*Chromaticity*/
0xff, 0xff, 0xff, /*Established timing bitmap*/
0x00, 0x00, /*Standard timing information*/
0x00, 0x00,
0x00, 0x00,
0x00, 0x00,
0x00, 0x00,
0x00, 0x00,
0x00, 0x00,
0x00, 0x00,
/*Detailed mode descriptions*/
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, /*No extensions*/
0x00
};
/*This should probably be split off into a separate I2C module*/
enum
{
TRANSMITTER_MONITOR = 1,
TRANSMITTER_HOST = -1
};
enum
{
I2C_IDLE = 0,
I2C_RECEIVE,
I2C_RECEIVE_WAIT,
I2C_TRANSMIT_START,
I2C_TRANSMIT,
I2C_ACKNOWLEDGE,
I2C_TRANSACKNOWLEDGE,
I2C_TRANSMIT_WAIT
};
enum
{
PROM_IDLE = 0,
PROM_RECEIVEADDR,
PROM_RECEIVEDATA,
PROM_SENDDATA,
PROM_INVALID
};
static struct
{
int clock, data;
int state;
int last_data;
int pos;
int transmit;
uint8_t byte;
} i2c;
static struct
{
int state;
int addr;
int rw;
} prom;
static void prom_stop(void)
{
// pclog("prom_stop()\n");
prom.state = PROM_IDLE;
i2c.transmit = TRANSMITTER_HOST;
}
static void prom_next_byte(void)
{
// pclog("prom_next_byte(%d)\n", prom.addr);
i2c.byte = edid_data[(prom.addr++) & 0x7F];
}
static void prom_write(uint8_t byte)
{
// pclog("prom_write: byte=%02x\n", byte);
switch (prom.state)
{
case PROM_IDLE:
if ((byte & 0xfe) != 0xa0)
{
// pclog("I2C address not PROM\n");
prom.state = PROM_INVALID;
break;
}
prom.rw = byte & 1;
if (prom.rw)
{
prom.state = PROM_SENDDATA;
i2c.transmit = TRANSMITTER_MONITOR;
i2c.byte = edid_data[(prom.addr++) & 0x7F];
// pclog("PROM - %02X from %02X\n",i2c.byte, prom.addr-1);
// pclog("Transmitter now PROM\n");
}
else
{
prom.state = PROM_RECEIVEADDR;
i2c.transmit = TRANSMITTER_HOST;
}
// pclog("PROM R/W=%i\n",promrw);
return;
case PROM_RECEIVEADDR:
// pclog("PROM addr=%02X\n",byte);
prom.addr = byte;
if (prom.rw)
prom.state = PROM_SENDDATA;
else
prom.state = PROM_RECEIVEDATA;
break;
case PROM_RECEIVEDATA:
// pclog("PROM write %02X %02X\n",promaddr,byte);
break;
case PROM_SENDDATA:
break;
}
}
void ddc_i2c_change(int new_clock, int new_data)
{
// pclog("I2C update clock %i->%i data %i->%i state %i\n",i2c.clock,new_clock,i2c.last_data,new_data,i2c.state);
switch (i2c.state)
{
case I2C_IDLE:
if (i2c.clock && new_clock)
{
if (i2c.last_data && !new_data) /*Start bit*/
{
// pclog("Start bit received\n");
i2c.state = I2C_RECEIVE;
i2c.pos = 0;
}
}
break;
case I2C_RECEIVE_WAIT:
if (!i2c.clock && new_clock)
i2c.state = I2C_RECEIVE;
case I2C_RECEIVE:
if (!i2c.clock && new_clock)
{
i2c.byte <<= 1;
if (new_data)
i2c.byte |= 1;
else
i2c.byte &= 0xFE;
i2c.pos++;
if (i2c.pos == 8)
{
prom_write(i2c.byte);
i2c.state = I2C_ACKNOWLEDGE;
}
}
else if (i2c.clock && new_clock && new_data && !i2c.last_data) /*Stop bit*/
{
// pclog("Stop bit received\n");
i2c.state = I2C_IDLE;
prom_stop();
}
else if (i2c.clock && new_clock && !new_data && i2c.last_data) /*Start bit*/
{
// pclog("Start bit received\n");
i2c.pos = 0;
prom.state = PROM_IDLE;
}
break;
case I2C_ACKNOWLEDGE:
if (!i2c.clock && new_clock)
{
// pclog("Acknowledging transfer\n");
new_data = 0;
i2c.pos = 0;
if (i2c.transmit == TRANSMITTER_HOST)
i2c.state = I2C_RECEIVE_WAIT;
else
i2c.state = I2C_TRANSMIT;
}
break;
case I2C_TRANSACKNOWLEDGE:
if (!i2c.clock && new_clock)
{
if (new_data) /*It's not acknowledged - must be end of transfer*/
{
// pclog("End of transfer\n");
i2c.state = I2C_IDLE;
prom_stop();
}
else /*Next byte to transfer*/
{
i2c.state = I2C_TRANSMIT_START;
prom_next_byte();
i2c.pos = 0;
// pclog("Next byte - %02X\n",i2c.byte);
}
}
break;
case I2C_TRANSMIT_WAIT:
if (i2c.clock && new_clock)
{
if (i2c.last_data && !new_data) /*Start bit*/
{
prom_next_byte();
i2c.pos = 0;
// pclog("Next byte - %02X\n",i2c.byte);
}
if (!i2c.last_data && new_data) /*Stop bit*/
{
// pclog("Stop bit received\n");
i2c.state = I2C_IDLE;
prom_stop();
}
}
break;
case I2C_TRANSMIT_START:
if (!i2c.clock && new_clock)
i2c.state = I2C_TRANSMIT;
if (i2c.clock && new_clock && !i2c.last_data && new_data) /*Stop bit*/
{
// pclog("Stop bit received\n");
i2c.state = I2C_IDLE;
prom_stop();
}
case I2C_TRANSMIT:
if (!i2c.clock && new_clock)
{
i2c.clock = new_clock;
// if (!i2c.pos)
// pclog("Transmit byte %02x\n", i2c.byte);
i2c.data = new_data = i2c.byte & 0x80;
// pclog("Transmit bit %i %i\n", i2c.byte, i2c.pos);
i2c.byte <<= 1;
i2c.pos++;
return;
}
if (i2c.clock && !new_clock && i2c.pos == 8)
{
i2c.state = I2C_TRANSACKNOWLEDGE;
// pclog("Acknowledge mode\n");
}
break;
}
if (!i2c.clock && new_clock)
i2c.data = new_data;
i2c.last_data = new_data;
i2c.clock = new_clock;
}
int ddc_read_clock(void)
{
return i2c.clock;
}
int ddc_read_data(void)
{
if (i2c.state == I2C_TRANSMIT || i2c.state == I2C_ACKNOWLEDGE)
return i2c.data;
if (i2c.state == I2C_RECEIVE_WAIT)
return 0; /*ACK*/
return 1;
}
void ddc_init(void)
{
int c;
uint8_t checksum = 0;
for (c = 0; c < 127; c++)
checksum += edid_data[c];
edid_data[127] = 256 - checksum;
i2c.clock = 1;
i2c.data = 1;
}
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