Uncompressed Index files (*.idx)
_______________________ _______
00h / 0 | Pointer to root node | ^
01h / 1 | | |
02h / 2 | | |
03h / 3 | | |
|-----------------------| |
04h / 4 | Pointer to free list | File
05h / 5 | (-1 if empty) | header
06h / 6 | | |
07h / 7 | *3| |
|-----------------------| |
08h / 8 | Pointer to EOF | |
09h / 9 | | |
0Ah / 10 | | |
0Bh / 11 | | |
|-----------------------| |
0Ch / 12 | Key length | |
0Dh / 13 | *4| |
|-----------------------| |
0Eh / 14 | Index options *1| |
|-----------------------| |
0Fh / 15 | Index Signature | |
|-----------------------| |
10h / 16 | Key expression | |
11h / 17 | | |
: : |
: : |
EBh / 235| | |
|-----------------------| |
ECh / 236| FOR expression | |
| | |
: : |
: : |
1C7h / 455| | |
|-----------------------| |
1C8h / 456| (Reserved) | |
| | |
: : |
: : |
1FFh / 511| | |
|=======================| _v____
00h / 0 | Node attributes *2| ^
01h / 1 | | |
|-----------------------| |
02h / 2 | Number of keys *6| |
03h / 3 | | |
|-----------------------| Non
04h / 4 | Pointer to left | leaf
05h / 5 | brother node | page
06h / 6 | (-1 if no left node) | |
07h / 7 | | (compressed)
|-----------------------| |
08h / 8 | Pointer to right | |
09h / 9 | brother node | |
0Ah / 10 | (-1 if no right node) | |
0Bh / 11 | | |
|-----------------------| |
0Ch / 12 | | |
| | | __ |=======================|
| | | / M| Key data |
| | NON / : :
: : leaf / : :
: : page / N| |
: : | / |-----------------------|
| Array of key entries | _|_____/ O| Record number in *5|
| | _|______ | data file |
| | | \ | (Big endian binary) |
| | | \ O+4| |
1FFh / 511| | | \____ |=======================|
|=======================| _v_____
- Index options
represented as the sum of the following values:
|
Value
|
Description
|
|
01
|
Unique index
|
|
08
|
FOR clause
|
|
16 (10h)
|
Bit vector (SoftC)
|
|
32 (20h)
|
Compact index format (FoxPro)
|
|
64 (40h)
|
Compounding index header (FoxPro)
|
|
128 (80h)
|
Structure index (FoxPro)
|
- Node attributes
represented as the sum of the following values:
|
Value
|
Description
|
|
0
|
Index node
|
|
1
|
Start page
|
|
2
|
End page
|
- Pointer value
:
|
Value
|
Description
|
|
-1 (= FFh FFh FFh FFh)
|
if none (FoxPro)
|
|
0
|
if none (FoxBase)
|
- Node attributes
represented as the sum of the following values:
|
Value
|
Description
|
|
4
|
Number and date keys are 8 bits long . Character keys are <= 100
bytes long.
Note! Character keys are NOT terminated with 00h
|
|
-1
|
if none (FoxPro)
|
|
0
|
if none (FoxBase)
|
- Pointer
Interpretated by attrbute
type
|
Value
|
Description
|
|
0-1
|
Pointer to next lowest not containg section for tree
|
|
2-3
|
Pointer to record in data file
|
- ??
Must be in the interval 0 - 100, where 0 is empty
Schematic Tree structure in uncompresse FoxPro idx
____ ________ ____
| | | |
| -1 | F, H | -1 |
|____|__|__|__|____|
| |
________| |__________
_ __ _____|__ ____ ____ ___|____ ____
| | V | | | | V | |
| -1 | C, F | *-+-----+-* | H | -1 |
|____|__|__|__|____| |____|___|____|____|
| | |
________| |____________ |______________
____ _____|__ ____ ____ _____|__ ____ ____ _____|__ ____
| | V | | | | V | | | | V | |
| -1 | A B C | *-+-----+-* | D E F | *-+-----+-* | G, H | -1 |
|____|________|____| |____|________|____| |____|________|____|