dingusppc/devices/dbdma.h

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/*
DingusPPC - The Experimental PowerPC Macintosh emulator
Copyright (C) 2018-20 divingkatae and maximum
(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/>.
*/
/** @file Descriptor-based direct memory access emulation.
Official documentation can be found in the fifth chapter of the book
"Macintosh Technology in the Common Hardware Reference Platform"
by Apple Computer, Inc.
*/
#ifndef DB_DMA_H
#define DB_DMA_H
#include <cinttypes>
/** DBDMA Channel registers offsets */
enum DMAReg : uint32_t {
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CH_CTRL = 0,
CH_STAT = 4,
CMD_PTR_LO = 12,
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};
/** Channel Status bits (DBDMA spec, 5.5.3) */
enum {
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CH_STAT_ACTIVE = 0x400,
CH_STAT_DEAD = 0x800,
CH_STAT_WAKE = 0x1000,
CH_STAT_FLUSH = 0x2000,
CH_STAT_PAUSE = 0x4000,
CH_STAT_RUN = 0x8000
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};
/** DBDMA command (DBDMA spec, 5.6.1) - all fields are little-endian! */
typedef struct DMACmd {
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uint16_t req_count;
uint8_t cmd_bits;
uint8_t cmd_key;
uint32_t address;
uint32_t cmd_arg;
uint16_t res_count;
uint16_t xfer_stat;
} DMACmd;
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class DMACallback {
public:
virtual void dma_start(void) = 0;
virtual void dma_end(void) = 0;
//virtual void dma_push(uint8_t *buf, int size) = 0;
//virtual void dma_pull(uint8_t *buf, int size) = 0;
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};
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class DMAChannel {
public:
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DMAChannel(DMACallback* cb) {
this->dma_cb = cb;
};
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~DMAChannel() = default;
uint32_t reg_read(uint32_t offset, int size);
void reg_write(uint32_t offset, uint32_t value, int size);
int get_data(uint32_t req_len, uint32_t *avail_len, uint8_t **p_data);
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bool is_active();
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protected:
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void get_next_cmd(uint32_t cmd_addr, DMACmd* p_cmd);
uint8_t interpret_cmd(void);
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void start(void);
void resume(void);
void abort(void);
void pause(void);
private:
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DMACallback* dma_cb = 0;
uint16_t ch_stat = 0;
uint32_t cmd_ptr = 0;
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uint32_t queue_len;
uint8_t* queue_data;
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};
#endif /* DB_DMA_H */