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73 lines
2.6 KiB
Markdown
73 lines
2.6 KiB
Markdown
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[](https://github.com/marketplace/actions/arduino_ci)
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[](https://github.com/RobTillaart/nibbleArray/actions/workflows/arduino-lint.yml)
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[](https://github.com/RobTillaart/nibbleArray/actions/workflows/jsoncheck.yml)
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[](https://github.com/RobTillaart/nibbleArray/blob/master/LICENSE)
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[](https://github.com/RobTillaart/nibbleArray/releases)
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# nibbleArray
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Arduino library for a compact array of nibbles (4 bit units).
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## Description
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A nibble is a 4 bit element, which can hold a value 0..15 (0..F in HEX).
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It can be seen as an **uint4_t** type.
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The nibbleArray is an array that stores 2 nibbles in a byte therefore it is
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twice as small as a normal array.
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The current implementation can hold 510 elements. This is due a limitation of
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the UNO which can **alloc** max 255 bytes in one **malloc()** call.
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This **NIBBLEARRAY_MAXSIZE** can be defined compile time "-D NIBBLEARRAY_MAXSIZE"
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or one can adjust it in the library if other platforms can allocate more memory.
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## Interface
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The interface of the nibbleArray is straightforward:
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- **nibbleArray(uint16_t size)** constructor
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- **uint8_t set(uint16_t index, uint8_t value)** set a value in the nibbleArray.
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Index must be in range otherwise 0xFF = NIBBLEARRAY_ERROR_INDEX will be returned.
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If value > 15 it will be truncated.
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- **uint8_t get(uint16_t index)** get value from the nibbleArray.
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Index must be in range otherwise 0xFF = NIBBLEARRAY_ERROR_INDEX will be returned.
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- **uint16_t size()** returns the size of the array.
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- **uint16_t memory()** returns the memory used in bytes.
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- **void clear()** set all elements to 0.
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- **void SetAll(uint8_t value)** set all elements to value (0..15).
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If value > 15 it will be truncated.
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## Operation
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See examples
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## Future
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#### must
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- align interface with boolArray and bitArray.
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- is there some base class?
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- align error codes.
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- add a begin() function that does the work now done in constructor
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- allow larger allocations for non AVR, how?
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- don't test for size, user responsibility?
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#### could
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- implement NIBBLEARRAY_ERROR_VALUE for set and setAll ??
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- for now user responsibility.
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#### won't
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- setAll( f() ) - fill the array by calling a function n times?
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