mirror of
https://github.com/dingusdev/dingusppc.git
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143 lines
4.1 KiB
C++
143 lines
4.1 KiB
C++
/*
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DingusPPC - The Experimental PowerPC Macintosh emulator
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Copyright (C) 2018-22 divingkatae and maximum
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(theweirdo) spatium
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(Contact divingkatae#1017 or powermax#2286 on Discord for more info)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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/** @file Athens clock generator emulation. */
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/**
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Athens (Apple part# 343S1191) is a programmable clock generator ASIC
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used in the PCI Power Macintosh computers.
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It has two outputs: system clock and video aka dot clock. Both can be
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programmed using HW jumpers or I2C interface.
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This high-level emulator focuses on the Athen's I2C interface providing
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methods for querying the resulting virtual frequences.
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This is helpful especially for calculating video parameters.
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*/
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#include <devices/common/i2c/athens.h>
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#include <loguru.hpp>
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#include <algorithm>
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#include <cinttypes>
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#include <vector>
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AthensClocks::AthensClocks(uint8_t dev_addr)
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{
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supports_types(HWCompType::I2C_DEV);
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this->my_addr = dev_addr;
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// set up power on values
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this->regs[AthensRegs::P2_MUX2] = 0x62;
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}
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void AthensClocks::start_transaction()
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{
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this->pos = 0; // reset read/write position
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}
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bool AthensClocks::send_subaddress(uint8_t sub_addr)
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{
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LOG_F(INFO, "Athens: subaddress set to 0x%X", sub_addr);
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return true;
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}
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bool AthensClocks::send_byte(uint8_t data)
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{
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switch (this->pos) {
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case 0:
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this->reg_num = data;
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this->pos++;
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break;
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case 1:
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if (this->reg_num >= ATHENS_NUM_REGS) {
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LOG_F(WARNING, "Athens: invalid register number %d", this->reg_num);
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return false; // return NACK
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}
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this->regs[this->reg_num] = data;
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if (reg_num == 3) {
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LOG_F(INFO, "Athens: dot clock frequency set to %d Hz", get_dot_freq());
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}
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break;
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default:
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LOG_F(WARNING, "Athens: too much data received!");
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return false; // return NACK
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}
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return true;
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}
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bool AthensClocks::receive_byte(uint8_t* p_data)
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{
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*p_data = 0x41; // return my ID (value has been guessed)
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return true;
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}
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int AthensClocks::get_sys_freq()
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{
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return 0;
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}
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int AthensClocks::get_dot_freq()
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{
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static std::vector<int> D2_commons = {7, 11, 13, 14, 15, 17, 23, 31};
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static std::vector<int> N2_commons = {
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22, 27, 28, 31, 35, 37, 38, 42, 49, 55, 56, 78, 125
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};
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if (this->regs[AthensRegs::P2_MUX2] & 0xC0) {
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LOG_F(INFO, "Athens: dot clock disabled");
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return 0;
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}
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float out_freq = 0.0f;
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int d2 = this->regs[AthensRegs::D2];
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int n2 = this->regs[AthensRegs::N2];
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int post_div = 1 << (3 - (this->regs[AthensRegs::P2_MUX2] & 3));
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if (std::find(D2_commons.begin(), D2_commons.end(), d2) == D2_commons.end()) {
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LOG_F(WARNING, "Athens: untested D2 value %d", d2);
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}
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if (std::find(N2_commons.begin(), N2_commons.end(), n2) == N2_commons.end()) {
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LOG_F(WARNING, "Athens: untested N2 value %d", d2);
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}
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int mux = (this->regs[AthensRegs::P2_MUX2] >> 4) & 3;
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switch (mux) {
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case 0: // clock source -> dot cock VCO
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out_freq = ATHENS_XTAL * ((float)n2 / (float)(d2 * post_div));
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break;
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case 1: // clock source -> system clock VCO
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LOG_F(WARNING, "Athens: system clock VCO not supported yet!");
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break;
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case 2: // clock source -> crystal frequency
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out_freq = ATHENS_XTAL / post_div;
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break;
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case 3:
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LOG_F(WARNING, "Athens: attempt to use reserved Mux value!");
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break;
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}
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return static_cast<int>(out_freq + 0.5f);
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}
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