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/*
RCC-Project
Copyright (C) 2026 Richard Qin
This file is part of RCC-Project.
RCC-Project 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.
RCC-Project 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
RCC-Project; see the file COPYING. If not see
<http://www.gnu.org/licenses/>.
*/
#include "bios.h"
#include "io.h"
#define ATA_DATA 0x1F0u
#define ATA_SECTOR_COUNT 0x1F2u
#define ATA_LBA_LOW 0x1F3u
#define ATA_LBA_MID 0x1F4u
#define ATA_LBA_HIGH 0x1F5u
#define ATA_DRIVE 0x1F6u
#define ATA_STATUS 0x1F7u
#define ATA_COMMAND 0x1F7u
#define ATA_STATUS_ERR 0x01u
#define ATA_STATUS_DRQ 0x08u
#define ATA_STATUS_BSY 0x80u
#define ATA_CMD_READ_SECTORS 0x20u
static u8
ata_wait_not_busy (void)
{
u8 status;
do
{
status = io_in8 (ATA_STATUS);
}
while ((status & ATA_STATUS_BSY) != 0);
return status;
}
static void
ata_delay_400ns (void)
{
io_in8 (ATA_STATUS);
io_in8 (ATA_STATUS);
io_in8 (ATA_STATUS);
io_in8 (ATA_STATUS);
}
static u8
ata_read_one_sector28 (u32 lba, u16 *buffer)
{
u8 status;
u16 index;
status = ata_wait_not_busy ();
if ((status & ATA_STATUS_ERR) != 0)
return 1;
io_out8 (ATA_DRIVE, (u8)(0xE0u | ((lba >> 24) & 0x0Fu)));
ata_delay_400ns ();
io_out8 (ATA_SECTOR_COUNT, 1);
io_out8 (ATA_LBA_LOW, (u8)(lba & 0xFFu));
io_out8 (ATA_LBA_MID, (u8)((lba >> 8) & 0xFFu));
io_out8 (ATA_LBA_HIGH, (u8)((lba >> 16) & 0xFFu));
io_out8 (ATA_COMMAND, ATA_CMD_READ_SECTORS);
status = ata_wait_not_busy ();
if ((status & ATA_STATUS_ERR) != 0)
return 1;
if ((status & ATA_STATUS_DRQ) == 0)
return 1;
for (index = 0; index < 256; ++index)
buffer[index] = io_in16 (ATA_DATA);
return 0;
}
u8
ata_read_sectors28 (u32 lba, u16 *buffer, u16 count)
{
u16 sector;
if (count == 0u)
return 1;
for (sector = 0; sector < count; ++sector)
{
if (ata_read_one_sector28 (lba, buffer) != 0)
return 1;
lba++;
buffer += 256;
}
return 0;
}
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