ra8_bit_constants.h File Reference

Named Bit Positions and Masks for Register Manipulation. More...

#include <stdint.h>

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Enumerations
enum	ra8_bit_position_t : uint8_t {   k_ra8_bit_0 = 0U ,   k_ra8_bit_1 = 1U ,   k_ra8_bit_2 = 2U ,   k_ra8_bit_3 = 3U ,   k_ra8_bit_4 = 4U ,   k_ra8_bit_5 = 5U ,   k_ra8_bit_6 = 6U ,   k_ra8_bit_7 = 7U ,   k_ra8_bit_8 = 8U ,   k_ra8_bit_9 = 9U ,   k_ra8_bit_10 = 10U ,   k_ra8_bit_11 = 11U ,   k_ra8_bit_12 = 12U ,   k_ra8_bit_13 = 13U ,   k_ra8_bit_14 = 14U ,   k_ra8_bit_15 = 15U ,   k_ra8_bit_16 = 16U ,   k_ra8_bit_17 = 17U ,   k_ra8_bit_18 = 18U ,   k_ra8_bit_19 = 19U ,   k_ra8_bit_20 = 20U ,   k_ra8_bit_21 = 21U ,   k_ra8_bit_22 = 22U ,   k_ra8_bit_23 = 23U ,   k_ra8_bit_24 = 24U ,   k_ra8_bit_25 = 25U ,   k_ra8_bit_26 = 26U ,   k_ra8_bit_27 = 27U ,   k_ra8_bit_28 = 28U ,   k_ra8_bit_29 = 29U ,   k_ra8_bit_30 = 30U ,   k_ra8_bit_31 = 31U }
	Bit positions 0..31 as typed constants. More...
enum	ra8_byte_mask_t : uint16_t {   k_ra8_mask_nibble = 0x000FU ,   k_ra8_mask_byte = 0x00FFU ,   k_ra8_mask_word = 0xFFFFU ,   k_ra8_mask_lsn2 = 0x0003U ,   k_ra8_mask_lsn3 = 0x0007U ,   k_ra8_mask_lsn4 = 0x000FU ,   k_ra8_mask_lsn5 = 0x001FU ,   k_ra8_mask_lsn6 = 0x003FU ,   k_ra8_mask_lsn7 = 0x007FU ,   k_ra8_mask_lsn8 = 0x00FFU }
	Byte-wide bit masks and positions for byte packing/unpacking. More...
enum	ra8_byte_count_t : uint8_t {   k_ra8_bits_per_byte = 8U ,   k_ra8_bits_per_u16 = 16U ,   k_ra8_bits_per_u32 = 32U ,   k_ra8_bits_per_u64 = 64U }
	Bit counts per integral type. More...
enum	ra8_be_byte_idx_t : uint8_t {   k_ra8_be_idx_hi32 = 0U ,   k_ra8_be_idx_mh32 = 1U ,   k_ra8_be_idx_ml32 = 2U ,   k_ra8_be_idx_lo32 = 3U ,   k_ra8_be_idx_hi16 = 0U ,   k_ra8_be_idx_lo16 = 1U }
	Byte indices when packing big-endian multi-byte values. More...

Detailed Description

Named Bit Positions and Masks for Register Manipulation.

Central home for bit-position constants used when poking hardware registers. Every bit shift and mask in the firmware should be expressed in terms of one of these enums rather than a raw integer literal. The clang-tidy rule readability-magic-numbers enforces this at commit time.

Why this exists

Without named constants, register writes look like:

reg->CR |= (1U << 7) | (3U << 3);  // what bit? why 3?

With this header, they look like:

reg->CR |= (k_ra8_bit_1 << k_ra8_bit_7) | (k_ra8_mask_lsn2 << k_ra8_bit_3);

The second version is searchable (grep k_ra8_bit_7 tells you every place bit 7 is touched), self-documenting, and compile-time type-safe.

Copyright

Copyright (c) 2026 Brighton Sikarskie SPDX-License-Identifier: MIT

Definition in file ra8_bit_constants.h.

Enumeration Type Documentation

ra8_be_byte_idx_t

enum ra8_be_byte_idx_t : uint8_t

Byte indices when packing big-endian multi-byte values.

Use in place of raw literals when splitting a uint16_t or uint32_t into a byte buffer. Keeps code self-documenting and greppable.

buf[k_ra8_be_idx_hi16] = (uint8_t)(val >> k_ra8_bit_8);
buf[k_ra8_be_idx_lo16] = (uint8_t)(val & k_ra8_mask_byte);

Enumerator
k_ra8_be_idx_hi32	Most significant byte of a 32-bit big-endian value.
k_ra8_be_idx_mh32	Mid-high byte.
k_ra8_be_idx_ml32	Mid-low byte.
k_ra8_be_idx_lo32	Least significant byte.
k_ra8_be_idx_hi16	Most significant byte of a 16-bit big-endian value.
k_ra8_be_idx_lo16	Least significant byte.

Definition at line 144 of file ra8_bit_constants.h.

ra8_bit_position_t

enum ra8_bit_position_t : uint8_t

Bit positions 0..31 as typed constants.

Use these with the shift operator to construct masks:

uint32_t mask = (1U << k_ra8_bit_5);  // 0x20

Every position is a distinct enumerator so the compiler's switch analysis and clang-tidy's naming rules both see them.

Enumerator
k_ra8_bit_0	RA8 bit 0.
k_ra8_bit_1	RA8 bit 1.
k_ra8_bit_2	RA8 bit 2.
k_ra8_bit_3	RA8 bit 3.
k_ra8_bit_4	RA8 bit 4.
k_ra8_bit_5	RA8 bit 5.
k_ra8_bit_6	RA8 bit 6.
k_ra8_bit_7	RA8 bit 7.
k_ra8_bit_8	RA8 bit 8.
k_ra8_bit_9	RA8 bit 9.
k_ra8_bit_10	RA8 bit 10.
k_ra8_bit_11	RA8 bit 11.
k_ra8_bit_12	RA8 bit 12.
k_ra8_bit_13	RA8 bit 13.
k_ra8_bit_14	RA8 bit 14.
k_ra8_bit_15	RA8 bit 15.
k_ra8_bit_16	RA8 bit 16.
k_ra8_bit_17	RA8 bit 17.
k_ra8_bit_18	RA8 bit 18.
k_ra8_bit_19	RA8 bit 19.
k_ra8_bit_20	RA8 bit 20.
k_ra8_bit_21	RA8 bit 21.
k_ra8_bit_22	RA8 bit 22.
k_ra8_bit_23	RA8 bit 23.
k_ra8_bit_24	RA8 bit 24.
k_ra8_bit_25	RA8 bit 25.
k_ra8_bit_26	RA8 bit 26.
k_ra8_bit_27	RA8 bit 27.
k_ra8_bit_28	RA8 bit 28.
k_ra8_bit_29	RA8 bit 29.
k_ra8_bit_30	RA8 bit 30.
k_ra8_bit_31	RA8 bit 31.

Definition at line 58 of file ra8_bit_constants.h.

ra8_byte_count_t

enum ra8_byte_count_t : uint8_t

Bit counts per integral type.

Enumerator
k_ra8_bits_per_byte	Bits in a byte.
k_ra8_bits_per_u16	Bits in a uint16_t.
k_ra8_bits_per_u32	Bits in a uint32_t.
k_ra8_bits_per_u64	Bits in a uint64_t.

Definition at line 119 of file ra8_bit_constants.h.

ra8_byte_mask_t

enum ra8_byte_mask_t : uint16_t

Byte-wide bit masks and positions for byte packing/unpacking.

Enumerator
k_ra8_mask_nibble	Low 4 bits mask.
k_ra8_mask_byte	Low 8 bits mask.
k_ra8_mask_word	Low 16 bits mask.
k_ra8_mask_lsn2	Low 2-bit field mask.
k_ra8_mask_lsn3	Low 3-bit field mask.
k_ra8_mask_lsn4	Low 4-bit field (alias).
k_ra8_mask_lsn5	Low 5-bit field mask.
k_ra8_mask_lsn6	Low 6-bit field mask.
k_ra8_mask_lsn7	Low 7-bit field mask.
k_ra8_mask_lsn8	Low 8-bit field (alias).

Definition at line 102 of file ra8_bit_constants.h.