mask.h

#ifndef MASK_H
#define MASK_H

#ifdef BAREMETAL
#include "baremetalsupport.h"
#else
#include <assert.h>
#endif
#include <stdint.h>



#define MASK(type, width)		(((type)1 << (width)) - 1)
// Top bit of unshift mask is in position (high - low)
// High is the top bit to modify, low is the bottom bit to modify.
#define MASK_ENABLE_BITS(type, high, low)		\
	((MASK(type, (high) - (low) + 1)) << low)

#define SET_BITS_FUNCTION(type)											\
static inline type type ## _set_bits(									\
		type original, uint32_t high, uint32_t low, type value) {		\
	type new_value = original & ~MASK_ENABLE_BITS(type, high, low);		\
	new_value |= value << low;											\
	return new_value;													\
}
/* These define
uint8_t_set_bits(...)
uint16_t_set_bits(...)
Expressed like this in comment for ease of grepping :)
*/
SET_BITS_FUNCTION(uint8_t);
SET_BITS_FUNCTION(uint16_t);

/* These define
uint8_t_get_bits(...)
uint16_t_get_bits(...)
*/
#define GET_BITS_FUNCTION(type)											\
static inline type type ## _get_bits(								\
		type source, uint32_t high, uint32_t low) {						\
	return (source & MASK_ENABLE_BITS(type, high, low)) >> low;			\
}

GET_BITS_FUNCTION(uint8_t);
GET_BITS_FUNCTION(uint16_t);

static inline uint32_t
uint32_mask(uint32_t width) {
	assert(width <= 32);
	return (MASK(uint32_t, width));
}

static inline uint32_t
uint32_mask_enable_bits(uint32_t high, uint32_t low) {
	assert(high >= low);
	assert(high < 31);	// doesn't work for 31
	return (MASK_ENABLE_BITS(uint32_t, high, low));
}

static inline uint64_t
uint64_mask(uint64_t width) {
	assert(width <= 64);
	return (MASK(uint64_t, width));
}

static inline uint64_t
page_base_address(uint64_t address) {
	return address & ~uint64_mask(12);
}

#ifdef TEST_MASK
#include <stdio.h>

#define TEST(high, low) \
	printf("Mask [%d, %d] = %x\n", high, low, MASK_ENABLE_BITS(high, low))

int
main(int argc, char* argv[])
{
	assert(uint64_mask(4)==0xf);
	assert(uint64_mask(12)==0xfff);
	assert(uint64_mask(29)==0x1fffffff);
	assert(uint64_mask(37)==0x1fffffffffLL);
	assert(uint32_mask(4)==0xf);
	assert(uint32_mask(12)==0xfff);
	assert(uint32_mask(29)==0x1fffffff);
//	assert(uint32_mask(37)==0xffffffffLL);

	printf("%#x\n",uint32_mask_enable_bits(29,0));
	assert(uint32_mask_enable_bits(29,0)==0x3fffffff);
//	printf("%#x\n",uint32_mask_enable_bits(31LL,0LL));
//	assert(uint32_mask_enable_bits(31,0)==0xffffffff);
	printf("%#x\n",uint32_mask_enable_bits(15,0));
	assert(uint32_mask_enable_bits(15,0)==0xffff);
	printf("%#x\n",uint32_mask_enable_bits(4,0));
	assert(uint32_mask_enable_bits(4,0)==0x1f);
	printf("%#x\n",uint32_mask_enable_bits(7,4));
	assert(uint32_mask_enable_bits(7,4)==0xf0);

	assert( MASK_ENABLE_BITS(uint16_t,7,4)==0xf0);
	printf("%#x, mask=%#x\n",uint16_t_get_bits(0x5678,7,4), MASK_ENABLE_BITS(uint16_t,7,4));
	assert(uint16_t_get_bits(0x5678,7,4)==0x7);
	return 0;
}
#endif

#endif