lookup_tables - GreatCowBASIC/Help GitHub Wiki

Lookup Tables

Overview

A lookup table is a list of values stored in the microcontroller’s memory and accessed using ReadTable.

Key Features

  • Efficient memory usage
  • Supports byte, word, long, and integer types
  • ASCII string definitions supported
  • Constants and inline calculations permitted
  • External data sources allowed

Note: Decimal values are not supported

Contents

Defining Tables

Single Values

Table TestDataSource
    12
    24
    36
    48
    60
    72
End Table

Multiple Values

Table TestDataSource
    12, 24, 36
    48, 60, 72
End Table

Constants & Calculations

#define calculation_constant 2

Table TestDataSource
    1 * calculation_constant
    2 * calculation_constant
    3 * calculation_constant
    8 * calculation_constant
    4 * calculation_constant
    5 * calculation_constant
End Table

String Tables

Simple Examples

Table Test_1
    "ABCDEFGHIJ"
End Table

Table MnuTxt_1
    "  Display_1    Display_2    Display_3  "
End Table

Table MnuTxt_2
    "1: Display"
    "2: System Setup"
    "3: Config 1"
    "4: Config 2"
    "5: Data Log"
    "6: Diagnostic"
    "7: Help+"
End Table

Equivalent Representations

  • "String1", "String2", "String3"
  • "String1String2String3"
  • "String1" "String2" "String3"

ASCII Escape Sequences

Escape Meaning
\a Beep
\b Backspace
\f Formfeed
\n or \l Newline
\r Carriage Return
\t Tab
\0 Null value (ASCII 0)
\&nnn ASCII character (decimal)
\\ Backslash
\" Double quote
\' Single quote

Reading Lookup Tables

Basic Reading

Dim TableCounter, Invalue as byte

CLS
For TableCounter = 1 to 6
  ReadTable TestDataSource, TableCounter, Invalue
  Print InValue
  Print ","
Next

Reading Table Length

Dim lengthoftable as word
ReadTable TestDataSource, 0, lengthoftable
Print lengthoftable

Importing from External File

graphic

#chip 16f877a
Table TestDataSource from "sourcefile.raw"

For nn = 1 to 10
  ReadTable TestDataSource, nn, inc
  Print inc
Next

graphic

EEPROM Table Storage

#chip 16F628

TableLoc = 2
ReadTable TestDataSource, TableLoc, SomeVar

EPWrite 1, 45  'Optional write

Table TestDataSource Store Data
    12
    24
    36
    48
    60
    72
End Table

EEPROM Limitations

  • Only BYTE values are supported
  • WORD, INTEGER, or LONG are not compatible with EEPROM tables

Reference

See: ReadTable

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