3B2/3b2_if.h

/* 3b2_cpu.h: AT&T 3B2 Model 400 Floppy (TMS2797NL) Header

   Copyright (c) 2017, Seth J. Morabito

   Permission is hereby granted, free of charge, to any person
   obtaining a copy of this software and associated documentation
   files (the "Software"), to deal in the Software without
   restriction, including without limitation the rights to use, copy,
   modify, merge, publish, distribute, sublicense, and/or sell copies
   of the Software, and to permit persons to whom the Software is
   furnished to do so, subject to the following conditions:

   The above copyright notice and this permission notice shall be
   included in all copies or substantial portions of the Software.

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   SOFTWARE.

   Except as contained in this notice, the name of the author shall
   not be used in advertising or otherwise to promote the sale, use or
   other dealings in this Software without prior written authorization
   from the author.
*/

#ifndef __3B2_IF_H__
#define __3B2_IF_H__

#include "3b2_defs.h"
#include "3b2_sysdev.h"
#include "3b2_sys.h"

typedef struct {
    uint8 data;
    uint8 cmd;
    uint8 cmd_type;
    uint8 status;
    uint8 track;
    uint8 sector;
    uint8 side;
    uint8 read_addr_ptr;
    int8  step_dir;
    t_bool drq;
} IF_STATE;


extern DEVICE if_dev;
extern DEBTAB sys_deb_tab[];
extern IF_STATE if_state;
extern t_bool if_irq;

#define IFBASE 0x4d000
#define IFSIZE 0x10

#define IF_STATUS_REG    0
#define IF_CMD_REG       0
#define IF_TRACK_REG     1
#define IF_SECTOR_REG    2
#define IF_DATA_REG      3

/* Status Bits */
#define IF_BUSY          0x01
#define IF_DRQ           0x02
#define IF_INDEX         0x02
#define IF_TK_0          0x04
#define IF_LOST_DATA     0x04
#define IF_CRC_ERR       0x08
#define IF_SEEK_ERR      0x10
#define IF_RNF           0x10
#define IF_HEAD_LOADED   0x20
#define IF_RECORD_TYPE   0x20
#define IF_WP            0x40
#define IF_NRDY          0x80

/* Type I Commands */
#define IF_RESTORE       0x00
#define IF_SEEK          0x10
#define IF_STEP          0x20
#define IF_STEP_T        0x30
#define IF_STEP_IN       0x40
#define IF_STEP_IN_T     0x50
#define IF_STEP_OUT      0x60
#define IF_STEP_OUT_T    0x70

/* Type II Commands */
#define IF_READ_SEC      0x80
#define IF_READ_SEC_M    0x90
#define IF_WRITE_SEC     0xA0
#define IF_WRITE_SEC_M   0xB0

/* Type III Commands */
#define IF_READ_ADDR     0xC0
#define IF_READ_TRACK    0xE0
#define IF_WRITE_TRACK   0xF0

/* Type IV Command */
#define IF_FORCE_INT     0xD0

/* Command flags */

#define IF_C_FLAG        0x02
#define IF_V_FLAG        0x04
#define IF_E_FLAG        0x04
#define IF_U_FLAG        0x02
#define IF_H_FLAG        0x08
#define IF_S_FLAG        0x10

/* Constants */

#define IF_SIDES         2
#define IF_TRACK_SIZE    4608
#define IF_SECTOR_SIZE   512
#define IF_TRACK_COUNT   80

#define IF_STEP_IN_DIR    1
#define IF_STEP_OUT_DIR  -1

#define IF_DSK_SIZE      (IF_SIDES * IF_TRACK_SIZE * IF_TRACK_COUNT)

/* Function prototypes */

static SIM_INLINE void if_set_irq();
static SIM_INLINE void if_clear_irq();
static SIM_INLINE void if_cancel_pending_irq();
t_stat if_svc(UNIT *uptr);
t_stat if_reset(DEVICE *dptr);
uint32 if_read(uint32 pa, size_t size);
void if_write(uint32 pa, uint32 val, size_t size);
void if_drq_handled();
void if_handle_command();
uint32 if_buf_offset();

#endif