avr-lib/lib/calc.h

#pragma once

//
// Bit and byte manipulation utilities
//


// --- Increment in range ---
// when overflown, wraps within range. Lower bound < upper bound.
// ..., upper bound excluded
#define inc_wrap(var, min, max)  { if ((var) >= (max - 1)) { (var) = (min); } else { (var)++; } }
// ..., upper bound included
#define inc_wrapi(var, min, max) inc_wrap((var), (min), (max) + 1)


// --- Decrement in range ---
// when underflown, wraps within range. Lower bound < upper bound.
// ..., upper bound excluded
#define dec_wrap(var, min, max)  { if ((var) <= (min)) { (var) = (max) - 1; } else { (var)--; } }
// ..., upper bound included
#define dec_wrapi(var, min, max) dec_wrap((var), (min), (max) + 1)


// --- Bit manipulation --

// Set bit
#define sbi(reg, bit) { (reg) |=  (1 << (uint8_t)(bit)); }

// Clear bit
#define cbi(reg, bit) { (reg) &= ~(1 << (uint8_t)(bit)); }

// Get n-th bit
#define get_bit(reg, bit) (((reg) >> (uint8_t)(bit)) & 0x1)

// Test n-th bit (Can't use bit_is_set, as it's redefined in sfr_def.h)
#define bit_is_high(reg, bit) get_bit(reg, bit)
#define bit_is_low(reg, bit)  (!get_bit(reg, bit))

// Write value to n-th bit
#define set_bit(reg, bit, value) { (reg) = ((reg) & ~(1 << (uint8_t)(bit))) | (((uint8_t)(value) & 0x1) << (uint8_t)(bit)); }

// Invert n-th bit
#define toggle_bit(reg, bit) { (reg) ^= (1 << (uint8_t)(bit)); }


// --- Bit manipulation with pointer to variable ---

// Set n-th bit in pointee
#define sbi_p(reg_p, bit) { (*(reg_p)) |=  (1 << (uint8_t)(bit)); }
// Clear n-th bit in pointee
#define cbi_p(reg_p, bit) { (*(reg_p)) &= ~(1 << (uint8_t)(bit)); }

// Get n-th bit in pointee
#define get_bit_p(reg_p, bit) ((*(reg_p) >> (uint8_t)(bit)) & 0x1)

// Test n-th bit in pointee (Can't use bit_is_set, as it's redefined in sfr_def.h)
#define bit_is_high_p(reg_p, bit) get_bit_p(reg_p, bit)
#define bit_is_low_p(reg_p, bit)  (!get_bit_p(reg_p, bit))

// Write value to a bit in pointee
#define set_bit_p(reg_p, bit, value) { *(reg_p) = (*(reg_p) & ~(1 << ((uint8_t)(bit) & 0x1))) | (((uint8_t)(value) & 0x1) << (uint8_t)(bit)); }
#define toggle_bit_p(reg_p, bit)     { *(reg_p) ^= (1 << (uint8_t)(bit)); }


// --- Nibble manipulation ---

// Replace nibble in a byte
#define set_low_nibble(reg, value)  { (reg) = ((reg) & 0xF0) | ((uint8_t)(value) & 0xF); }
#define set_high_nibble(reg, value) { (reg) = ((reg) & 0x0F) | (((uint8_t)(value) & 0xF) << 4); }

#define set_low_nibble_p(reg_p, value)  { *(reg_p) = (*(reg_p) & 0xF0) | ((uint8_t)(value) & 0xF); }
#define set_high_nibble_p(reg_p, value) { *(reg_p) = (*(reg_p) & 0x0F) | (((uint8_t)(value) & 0xF) << 4); }

#define low_nibble(x) ((uint8_t)(x) & 0xF)
#define high_nibble(x) (((uint8_t)(x) & 0xF0) >> 4)

// --- Range tests ---

// Test if X is within low..high, regardless of bounds order
#define in_range(x, low, high)  ((((low)  < (high)) && ((x) >= (low) && (x)  < (high))) || (((low) > (high)) && ((x) >= (high) && (x)  < (low))))
// ..., include greater bound
#define in_rangei(x, low, high) ((((low) <= (high)) && ((x) >= (low) && (x) <= (high))) || (((low) > (high)) && ((x) >= (high) && (x) <= (low))))

// Test if X in low..high, wrap around ends if needed.
#define in_range_wrap(x, low, high)  ((((low)  < (high)) && ((x) >= (low) && (x) < (high)))  || (((low) > (high)) && ((x) >= (low) || (x)  < (high))))
// ..., include upper bound
#define in_range_wrapi(x, low, high) ((((low) <= (high)) && ((x) >= (low) && (x) <= (high))) || (((low) > (high)) && ((x) >= (low) || (x) <= (high))))