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Merged
merged 3 commits into from
Apr 12, 2024
Merged

hgrosser: hash-list optimized, small improvements in parsing the file #104

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f2b7f81
hash-list optimized, small improvements in parsing the file
hg747 Apr 11, 2024
2e7606b
small improvements in asm function
hg747 Apr 11, 2024
afbd4a6
Merge branch 'main' into main
gcarreno Apr 12, 2024
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21 changes: 16 additions & 5 deletions entries/hgrosser/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -3,19 +3,24 @@
**1 billion row Challenge entry**

## Version
Version 1.0
Version 1.51

## How to compile
The program was developed with FPC 3.2.2 and Lazarus 2.2.4

## How to start
```
Usage: hgrosser <path to input file> [buffer size in kb (Default=128 kb)]
Example: hgrosser ./measurements.txt 128
Usage: <path to input file> <bit-width for hash-list (14..28)>
Example: hgrosser measurements.txt 15
- bit-width for hash-list: sets the size of the hash list, e.g. '16' => 65536 entries
```
There are no switches like `-i` etc, only values.

Please start the program 3 times with buffer sizes of '128', '192' and '256'.
### Optimizing the 2nd command line parameter

In theory the program should run faster with greater bit-widths for the hash-list (because of less collisions), but on my own computer (8 GB RAM) in praxis a small value of 15 is the fastest way, allthough this causes many collisions.

Please (if possible) try all values from 14 to 24 (maybe in a for-loop). Thanks a lot.

## How the program works
The Program works with 1 thread.
Expand All @@ -24,5 +29,11 @@ To speed things up:

- the input file is read via procedure 'blockread' ...
- into an AnsiString, so that function 'PosEx' can be used to parse it
- to manage the city names, a 'TFPHashList' is used
- to manage the city names, a self made hash-list is used
- temperatures are stored as integers (multiplied by 10)

## History

- Version 1.00: initial version
- Version 1.50: hash-list optimized, small improvements in parsing the file
- Version 1.51: small improvements in asm function
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