HP 3000 Manuals HP 3000 Manuals
Files
When your program declares a file, the compiler allocates space for the
file control block and the file buffer variable. The amount of space
allocated to each is fixed by the packing algorithm. The file is
8-byte-aligned.
Table 5-9 shows how the HP Pascal packing algorithm allocates file
components for textfiles and nontextfiles.
Table 5-9. Allocation of File Components
(HP Pascal Packing Algorithm)
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| | | |
| File Component | Textfile | Nontextfile |
| | | |
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| | | |
| Control block | 324 bytes | 320 bytes |
| | | |
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| | | |
| Buffer variable | 254 bytes | Size of component type |
| | | |
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Sometimes you can reduce file buffer size or increase file operation
speed by the way you declare a file. Compare the following file
definitions, their buffer sizes, and how you can write 100 integers to
them.
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| | | |
| Declaration | Buffer Size | How to Write 100 Integers to the |
| | | File |
| | | |
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| | | |
| | | |
| VAR | 4 bytes | FOR i:=1 TO 100 DO write(f,i); |
| f : FILE OF integer; | | |
| | | (100 calls to put) |
| | | |
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| | | |
| | | |
| VAR | 400 bytes | FOR i:=1 TO 100 DO f^[i]:=i; |
| f : FILE OF | | put(f); |
| ARRAY [1..100] | | |
| OF integer; | | (One call to put) |
| | | |
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