dingusppc/devices/displayid.cpp

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/*
DingusPPC - The Experimental PowerPC Macintosh emulator
Copyright (C) 2018-20 divingkatae and maximum
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(theweirdo) spatium
(Contact divingkatae#1017 or powermax#2286 on Discord for more info)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "displayid.h"
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#include <thirdparty/loguru/loguru.hpp>
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DisplayID::DisplayID() {
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/* Initialize Apple monitor codes */
this->std_sense_code = 6;
this->ext_sense_code = 0x2B;
/* Initialize DDC I2C bus */
this->next_state = I2CState::STOP;
this->prev_state = I2CState::STOP;
this->last_sda = 1;
this->last_scl = 1;
this->data_out = 0x3000;
this->data_ptr = 0;
/* DDC sense mode is on by default */
this->i2c_on = true;
}
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uint16_t DisplayID::set_result(uint8_t sda, uint8_t scl) {
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this->last_sda = sda;
this->last_scl = scl;
if (scl) {
this->data_out |= 0x1000;
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} else {
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this->data_out &= ~0x1000U;
}
if (sda) {
this->data_out |= 0x2000;
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} else {
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this->data_out &= ~0x2000U;
}
return this->data_out;
}
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uint16_t DisplayID::read_monitor_sense(uint16_t data, uint16_t dirs) {
uint8_t scl, sda;
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uint16_t result;
if ((dirs & 0x3100) == 0 && (data & 0x3100) == 0x3100) {
LOG_F(WARNING, "DisplayID: Hackish Monitor ID Switch activated!");
this->i2c_on = false;
}
if (this->i2c_on) {
/* if GPIO pins are in the output mode, pick up their values
In the input mode, GPIO pins will be read "high" */
scl = (dirs & 0x1000) ? !!(data & 0x1000) : 1;
sda = (dirs & 0x2000) ? !!(data & 0x2000) : 1;
return update_ddc_i2c(sda, scl);
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} else { /* Apple legacy monitor codes (see Technical Note HW30) */
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switch (dirs & 0x3100) {
case 0:
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result = ((this->std_sense_code & 6) << 11) | ((this->std_sense_code & 1) << 8);
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break;
case 0x2000: /* Sense line 2 is low */
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result = ((this->ext_sense_code & 0x20) << 7) | ((this->ext_sense_code & 0x10) << 4);
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break;
case 0x1000: /* Sense line 1 is low */
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result = ((this->ext_sense_code & 8) << 10) | ((this->ext_sense_code & 4) << 6);
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break;
case 0x100: /* Sense line 0 is low */
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result = ((this->ext_sense_code & 2) << 12) | ((this->ext_sense_code & 1) << 12);
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break;
default:
result = 0x3100U;
}
return result;
}
}
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uint16_t DisplayID::update_ddc_i2c(uint8_t sda, uint8_t scl) //(uint16_t data, uint16_t dirs)
{
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bool clk_gone_high = false;
if (scl != this->last_scl) {
this->last_scl = scl;
if (scl) {
clk_gone_high = true;
}
}
if (sda != this->last_sda) {
/* START = SDA goes high to low while SCL is high */
/* STOP = SDA goes low to high while SCL is high */
if (this->last_scl) {
if (!sda) {
LOG_F(9, "DDC-I2C: START condition detected!");
this->next_state = I2CState::DEV_ADDR;
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this->bit_count = 0;
} else {
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LOG_F(9, "DDC-I2C: STOP condition detected!");
this->next_state = I2CState::STOP;
}
}
return set_result(sda, scl);
}
if (!clk_gone_high) {
return set_result(sda, scl);
}
switch (this->next_state) {
case I2CState::STOP:
break;
case I2CState::ACK:
this->bit_count = 0;
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this->byte = 0;
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switch (this->prev_state) {
case I2CState::DEV_ADDR:
if ((dev_addr & 0xFE) == 0xA0) {
sda = 0; /* send ACK */
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} else {
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LOG_F(ERROR, "DDC-I2C: unknown device address 0x%X", this->dev_addr);
sda = 1; /* send NACK */
}
if (this->dev_addr & 1) {
this->next_state = I2CState::DATA;
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this->data_ptr = this->edid;
this->byte = *(this->data_ptr++);
} else {
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this->next_state = I2CState::REG_ADDR;
}
break;
case I2CState::REG_ADDR:
this->next_state = I2CState::DATA;
if (!this->reg_addr) {
sda = 0; /* send ACK */
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} else {
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LOG_F(ERROR, "DDC-I2C: unknown register address 0x%X", this->reg_addr);
sda = 1; /* send NACK */
}
break;
case I2CState::DATA:
this->next_state = I2CState::DATA;
if (dev_addr & 1) {
if (!sda) {
/* load next data byte */
this->byte = *(this->data_ptr++);
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} else {
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LOG_F(ERROR, "DDC-I2C: Oops! NACK received");
}
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} else {
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sda = 0; /* send ACK */
}
break;
}
break;
case I2CState::DEV_ADDR:
case I2CState::REG_ADDR:
this->byte = (this->byte << 1) | this->last_sda;
if (this->bit_count++ >= 7) {
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this->bit_count = 0;
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this->prev_state = this->next_state;
this->next_state = I2CState::ACK;
if (this->prev_state == I2CState::DEV_ADDR) {
LOG_F(9, "DDC-I2C: device address received, addr=0x%X", this->byte);
this->dev_addr = this->byte;
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} else {
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LOG_F(9, "DDC-I2C: register address received, addr=0x%X", this->byte);
this->reg_addr = this->byte;
}
}
break;
case I2CState::DATA:
sda = (this->byte >> (7 - this->bit_count)) & 1;
if (this->bit_count++ >= 7) {
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this->bit_count = 0;
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this->prev_state = this->next_state;
this->next_state = I2CState::ACK;
}
break;
}
return set_result(sda, scl);
}