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508be6458a
We were not encoding data properly, because in DOS 3.3 and ProDOS, sectors must be interleaved on disk media (whereas in the original image form, data is laid out in a linear fashion). This solves a bug where we erroneously encountered a "bad" opcode (a7) in the program code.
70 lines
1.8 KiB
C
70 lines
1.8 KiB
C
#ifndef _APPLE2_ENC_H_
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#define _APPLE2_ENC_H_
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#include "vm_bits.h"
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#include "vm_segment.h"
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/*
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* This is a magic number for the disk volume; I haven't experimented
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* with using other values for it, and this one in particular is used in
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* WinApple, so I went with it.
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*/
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#define ENC_VOLUME 0xfe
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/*
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* The number of tracks that a DOS 3.3 disk would have.
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*/
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#define ENC_NUM_TRACKS 35
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/*
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* The number of sectors within a single track of data for a DOS 3.3
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* disk.
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*/
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#define ENC_NUM_SECTORS 16
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/*
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* A decoded sector is 256 bytes long
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*/
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#define ENC_DSECTOR 0x100
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/*
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* And a track--being composed of 16 sectors--is 4096 bytes long, or 4k
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* bytes. (256 * 16 = 4096)
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*/
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#define ENC_DTRACK 0x1000
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/*
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* An encoded sector is 396 bytes long, and is comprised of a sector
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* header plus padding bytes both before _and_ after the data field.
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*/
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#define ENC_ESECTOR 0x18c
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/*
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* An encoded track contains 16 sectors, as mentioned for ENC_DTRACK.
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* But it also contains some additional padding (48 bytes-worth).
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*/
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#define ENC_ETRACK 0x18f0
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/*
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* A sector header consists of some byte markers--all byte markers in
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* 6-and-2 encoding are 3 bytes long--and also some metadata, such as
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* the track number, the sector number, the volume, and an XOR'd
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* combination of all three.
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*/
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#define ENC_ESECTOR_HEADER 0xe
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/*
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* The track header (as mentioned for ENC_ETRACK) is 48 bytes of--well,
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* nothing really, just padding.
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*/
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#define ENC_ETRACK_HEADER 0x30
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extern int apple2_enc_4n4(vm_segment *, int, vm_8bit);
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extern int apple2_enc_sector(vm_segment *, vm_segment *, int, int);
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extern int apple2_enc_sector_header(vm_segment *, int, int, int);
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extern int apple2_enc_track(vm_segment *, vm_segment *, const int *, int, int);
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extern vm_segment *apple2_enc_dos(vm_segment *, const int *);
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extern vm_segment *apple2_enc_nib(vm_segment *);
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#endif
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