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Reorganize encoded sizes/routines to align with reference nibble output

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(This is comparing to the output that we see from dsk2nib.)
This commit is contained in:
Peter Evans 2018-03-20 14:06:26 -05:00
parent f5e0de5bbc
commit 474104085c
3 changed files with 20 additions and 8 deletions
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2
include/apple2.dd.h
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@ -43,7 +43,7 @@ enum apple2_dd_mode {
* it is nibbilized with 6-and-2 encoding.
*/
#define _140K_ 143360
#define _140K_NIB_ 223440
#define _140K_NIB_ 233008
/*
* And this is the length of a disk that has been formatted as a nibble

4
include/apple2.enc.h
View File

@ -37,13 +37,13 @@
* An encoded sector is 396 bytes long, and is comprised of a sector
* header plus padding bytes both before _and_ after the data field.
*/
#define ENC_ESECTOR 0x18c
#define ENC_ESECTOR 0x1a0
/*
* An encoded track contains 16 sectors, as mentioned for ENC_DTRACK.
* But it also contains some additional padding (48 bytes-worth).
*/
#define ENC_ETRACK 0x18f0
#define ENC_ETRACK 0x1a00
/*
* A sector header consists of some byte markers--all byte markers in

22
src/apple2.enc.c
View File

@ -33,6 +33,14 @@ static vm_8bit gcr62[] = {
0xed, 0xee, 0xef, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff, // 30
};
/*
* Define the physical sector order in which we write encoded data
*/
static int physical_order[] = {
0x0, 0xD, 0xB, 0x9, 0x7, 0x5, 0x3, 0x1,
0xE, 0xC, 0xA, 0x8, 0x6, 0x4, 0x2, 0xF,
};
/*
* Encode the given DOS-formatted segment with 6-and-2 encoding. This
* can work for both DOS 3.3 and ProDOS images, but would fail with DOS
@ -119,7 +127,11 @@ apple2_enc_track(int sectype, vm_segment *dest, vm_segment *src,
}
for (sect = 0; sect < 16; sect++) {
soff = toff + (ENC_DSECTOR * apple2_dd_sector_num(sectype, sect));
int logsec = apple2_dd_sector_num(sectype, sect);
int physec = physical_order[sect];
soff = toff + (ENC_DSECTOR * logsec);
doff = orig + (ENC_ESECTOR * physec) + 48;
// Each sector has a header with some metadata, plus some
// markers and padding.
@ -127,7 +139,7 @@ apple2_enc_track(int sectype, vm_segment *dest, vm_segment *src,
doff += apple2_enc_sector(dest, src, doff, soff);
}
return doff - orig;
return ENC_ETRACK;
}
/*
@ -232,8 +244,8 @@ apple2_enc_sector(vm_segment *dest, vm_segment *src,
vm_segment_set(dest, doff++, 0xaa);
vm_segment_set(dest, doff++, 0xeb);
// At the conclusion of a sector, we write 27 self-sync bytes.
for (i = 0; i < 27; i++) {
// At the conclusion of a sector, we write 48 self-sync bytes.
for (i = 0; i < 48; i++) {
vm_segment_set(dest, doff++, 0xff);
}
@ -290,7 +302,7 @@ apple2_enc_sector_header(vm_segment *seg, int off,
// Write six (exactly six!) self-sync bytes following the epilogue,
// because the Disk II controller/RWTS method expect to find it.
for (int i = 0; i < 6; i++) {
for (int i = 0; i < 5; i++) {
vm_segment_set(seg, off++, 0xff);
}