lookup_tables.h File Reference

Lookup tables for the uMIDI firmware. More...

#include <stdint.h>
#include <avr/pgmspace.h>

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Functions
uint16_t	lookup_exp (uint8_t x)
	Looks up an exponential value in the corresponding table. More...
uint16_t	lookup_log (uint8_t x)
	Looks up the natural log value in the corresponding table. More...
uint16_t	lookup_sine (uint8_t x)
	Looks up a sine function value in the corresponding table. More...

Variables
const uint8_t	lookup_table_resolution
	Resolution (y-axis) of the lookup tables in bits. More...
const uint16_t	exp_table []
	Lookup table for an exponential function. More...
const uint16_t	log_table []
	Lookup table for the natural logaritm function. More...
const uint16_t	sine_table []
	Lookup table for the sine function. More...

Detailed Description

Lookup tables for the uMIDI firmware.

The tables are computed with the PERL script compute_lookup_tables.pl, which generates the file lookup_tables.c from scratch. The lookup tables are declared globally and used in other modules, so this is not a stand-alone module but rather a component of those modules.

Function Documentation

lookup_exp()

uint16_t lookup_exp ( uint8_t  x )

inline

Looks up an exponential value in the corresponding table.

This inline function does not check array bounds!

Parameters

x	index of the value in the table

Returns

the function value

lookup_log()

uint16_t lookup_log ( uint8_t  x )

inline

Looks up the natural log value in the corresponding table.

This inline function does not check array bounds!

Parameters

x	index of the value in the table

Returns

the function value

lookup_sine()

uint16_t lookup_sine ( uint8_t  x )

inline

Looks up a sine function value in the corresponding table.

This inline function does not check array bounds!

Parameters

x	index of the value in the table

Returns

the function value

Variable Documentation

exp_table

const uint16_t exp_table[]

Lookup table for an exponential function.

log_table

const uint16_t log_table[]

Lookup table for the natural logaritm function.

lookup_table_resolution

const uint8_t lookup_table_resolution

Resolution (y-axis) of the lookup tables in bits.

sine_table

const uint16_t sine_table[]

Lookup table for the sine function.