nibbleArray

Arduino library for a compact array of nibbles (4 bit units).

Description

A nibble is a 4 bit element, which can hold a value 0..15 (0..F in HEX). It can be seen as an uint4_t type.

The nibbleArray is an array that stores 2 nibbles in a byte therefore it is twice as small as a normal array.

The current implementation can hold 510 elements. This is due a limitation of the UNO which can alloc max 255 bytes in one malloc() call.

This NIBBLEARRAY_MAXSIZE can be defined compile time "-D NIBBLEARRAY_MAXSIZE" or one can adjust it in the library if other platforms can allocate more memory.

Interface

The interface of the nibbleArray is straightforward:

nibbleArray(uint16_t size) constructor
uint8_t set(uint16_t index, uint8_t value) set a value in the nibbleArray. Index must be in range otherwise 0xFF = NIBBLEARRAY_ERROR_INDEX will be returned. If value > 15 it will be truncated.
uint8_t get(uint16_t index) get value from the nibbleArray. Index must be in range otherwise 0xFF = NIBBLEARRAY_ERROR_INDEX will be returned.
uint16_t size() returns the size of the array.
uint16_t memory() returns the memory used in bytes.
void clear() set all elements to 0.
void SetAll(uint8_t value) set all elements to value (0..15). If value > 15 it will be truncated.

Operation

See examples

Future

must

align interface with boolArray and bitArray.
- is there some base class?
- align error codes.
add a begin() function that does the work now done in constructor
allow larger allocations for non AVR, how?
- don't test for size, user responsibility?

could

implement NIBBLEARRAY_ERROR_VALUE for set and setAll ??
- for now user responsibility.

won't

setAll( f() ) - fill the array by calling a function n times?

2.6 KiB Raw Blame History