Apple-2-Tools/dmolony-DiskBrowser
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tidying

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This commit is contained in:
Denis Molony 2018-08-07 19:22:31 +10:00
parent de3012e952
commit aac34c9095
1 changed files with 31 additions and 17 deletions
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42
src/com/bytezone/diskbrowser/disk/Nibblizer.java
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@ -225,8 +225,9 @@ class Nibblizer
private byte[] decode5and3 (byte[] buffer, int offset) private byte[] decode5and3 (byte[] buffer, int offset)
{ {
for (int i = 0; i <= 410; i++) // convert legal disk values to actual 5 bit values
decodeDos32a[i] = getByte (buffer[offset++]); for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_32; i++) // 411 bytes
decodeDos32a[i] = getByte5and3 (buffer[offset++]);
// reconstruct 410 bytes each with 5 bits // reconstruct 410 bytes each with 5 bits
byte chk = 0; byte chk = 0;
@ -238,11 +239,13 @@ class Nibblizer
assert (chk ^ decodeDos32a[ptr]) == 0; assert (chk ^ decodeDos32a[ptr]) == 0;
// rearrange 410 bytes into 256 // rearrange 410 bytes into 256
byte[] decodedBuffer = new byte[BLOCK_SIZE]; byte[] decodedBuffer = new byte[BLOCK_SIZE]; // 256 bytes
byte[] k = new byte[8]; byte[] k = new byte[8];
ptr = 0; ptr = 0;
int[] lines = { 0, 51, 102, 153, 204, 256, 307, 358 }; int[] lines = { 0, 51, 102, 153, 204, 256, 307, 358 }; // NB 255 is skipped
// process 8 disk bytes at a time, giving 5 valid bytes
// do this 51 times, giving 255 bytes
for (int i = 50; i >= 0; i--) for (int i = 50; i >= 0; i--)
{ {
for (int j = 0; j < 8; j++) for (int j = 0; j < 8; j++)
@ -264,13 +267,17 @@ class Nibblizer
decodedBuffer[ptr++] = k[j]; decodedBuffer[ptr++] = k[j];
} }
// last byte not yet tested // add last byte
decodedBuffer[255] = (byte) (decodeDos32b[255] | (decodeDos32b[409] >>> 3)); decodedBuffer[255] = (byte) (decodeDos32b[255] | (decodeDos32b[409] >>> 3));
return decodedBuffer; return decodedBuffer;
} }
private byte getByte (byte b) // ---------------------------------------------------------------------------------//
// getByte5and3
// ---------------------------------------------------------------------------------//
private byte getByte5and3 (byte b)
{ {
int val = (b & 0xFF) - 0xAB; // 0 - 84 int val = (b & 0xFF) - 0xAB; // 0 - 84
assert val >= 0 && val <= 84; assert val >= 0 && val <= 84;
@ -279,6 +286,19 @@ class Nibblizer
return (byte) (trans << 3); // left justify 5 bits return (byte) (trans << 3); // left justify 5 bits
} }
// ---------------------------------------------------------------------------------//
// getByte6and2
// ---------------------------------------------------------------------------------//
private byte getByte6and2 (byte b)
{
int val = (b & 0xFF) - 0x96; // 0 - 105
assert val >= 0 && val <= 105;
byte trans = (byte) (readTranslateTable6and2[val] - 1); // 0 - 63 (6 bits)
assert trans >= 0 && trans <= 63;
return (byte) (trans << 2); // left justify 6 bits
}
// ---------------------------------------------------------------------------------// // ---------------------------------------------------------------------------------//
// decode6and2 // decode6and2
// ---------------------------------------------------------------------------------// // ---------------------------------------------------------------------------------//
@ -286,14 +306,8 @@ class Nibblizer
private byte[] decode6and2 (byte[] buffer, int offset) private byte[] decode6and2 (byte[] buffer, int offset)
{ {
// convert legal disk values to actual 6 bit values // convert legal disk values to actual 6 bit values
for (int i = 0; i < decodeDos33a.length; i++) // 343 bytes for (int i = 0; i < BUFFER_WITH_CHECKSUM_SIZE_DOS_33; i++) // 343 bytes
{ decodeDos33a[i] = getByte6and2 (buffer[offset++]);
int val = (buffer[offset++] & 0xFF) - 0x96; // 0 - 105
assert val >= 0 && val <= 105;
byte trans = (byte) (readTranslateTable6and2[val] - 1); // 0 - 63 (6 bits)
assert trans >= 0 && trans <= 63;
decodeDos33a[i] = (byte) (trans << 2); // left-justify 6 bits
}
// reconstruct 342 bytes each with 6 bits // reconstruct 342 bytes each with 6 bits
byte chk = 0; byte chk = 0;