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74 lines
3.1 KiB
C
74 lines
3.1 KiB
C
/************************************************************************
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PCem: IBM 5150 cassette support
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Copyright (C) 2019 John Elliott <seasip.webmaster@gmail.com>
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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 2 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, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*************************************************************************/
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#ifndef _PZX_H_
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#define _PZX_H_
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typedef enum {
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PZX_CLOSED, /* File is not open */
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PZX_IDLE, /* File is open, no block loaded */
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PZX_IN_PULS, /* File is open, current block is a PULS block */
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PZX_IN_DATA, /* File is open, current block is a DATA block */
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PZX_IN_PAUS, /* File is open, current block is a PAUS block */
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} PZX_STATE;
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typedef struct pzxfile_t {
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FILE *input; /* Input PZX file */
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uint8_t *curblock; /* Currently-loaded block, if any */
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int level; /* Current signal level */
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PZX_STATE state; /* State machine current status */
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/* State variables for PULS */
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uint32_t puls_ptr; /* Pointer within PULS block */
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uint32_t puls_len; /* Length of PULS block */
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uint32_t puls_count; /* Count of pulses */
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uint32_t puls_duration; /* Duration of each pulse */
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uint32_t puls_remain; /* Time remaining in this pulse */
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/* State variables for PAUS */
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uint32_t paus_remain; /* Time remaining in this pause */
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/* State variables for DATA */
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uint32_t data_ptr; /* Pointer within DATA block */
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uint32_t data_bits; /* Count of bits */
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uint16_t data_tail; /* Length of pulse after last bit */
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uint8_t data_mask; /* Mask for current bit */
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uint8_t data_p0; /* Length of 0 encoding */
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uint8_t data_p1; /* Length of 1 encoding */
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int data_p; /* Current sequence being emitted */
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uint32_t data_w; /* Current waveform */
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uint32_t data_remain; /* Current data pulse time remaining */
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} pzxfile_t;
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uint8_t *pzx_load_block(FILE *fp);
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/* Initialise structure */
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void pzx_init(pzxfile_t *pzx);
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/* Open file for input */
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const char *pzx_open(pzxfile_t *pzx, FILE *fp);
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/* Close file */
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void pzx_close(pzxfile_t *pzx);
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/* Advance by 'time' samples (3.5MHz sample rate) and return current state */
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int pzx_advance(pzxfile_t *pzx, int time);
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#endif /* _PZX_H_ */
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