-rw-r--r-- 1570 libmceliece-20240726/crypto_kem/348864/vec/util.h raw
/*
  This file is for loading/storing data in a little-endian fashion
*/
// 20240508 djb: remove unused bitrev

#ifndef UTIL_H
#define UTIL_H

#include "gf.h"

#include <stdint.h>

static inline void store_i(unsigned char *out, uint64_t in, int i)
{
	int j;

	for (j = 0; j < i; j++)
		out[j] = (in >> (j * 8)) & 0xFF;
}

static inline void store_gf(unsigned char *dest, gf a)
{
	dest[0] = a & 0xFF;
	dest[1] = a >> 8;
}

static inline uint16_t load_gf(const unsigned char *src)
{
	uint16_t a;

	a = src[1];
	a <<= 8;
	a |= src[0];

	return a & GFMASK;
}

static inline uint32_t load4(const unsigned char *src)
{
	uint32_t a;

	a  = src[3]; a <<= 8; 
	a |= src[2]; a <<= 8;
	a |= src[1]; a <<= 8;
	a |= src[0];

	return a;
}

static inline void irr_load(uint64_t * out, const unsigned char * in)
{
	int i, j;
	uint16_t irr[ SYS_T + 1 ];	

	for (i = 0; i < SYS_T; i++) 
		irr[i] = load_gf(in + i*2);

	irr[ SYS_T ] = 1;

	for (i = 0; i < GFBITS; i++) 
		out[i] = 0;

	for (i = SYS_T; i >= 0; i--)
	for (j = 0; j < GFBITS; j++) 
	{
		out[j] <<= 1;
		out[j] |= (irr[i] >> j) & 1;
	}
}

static inline void store8(unsigned char *out, uint64_t in)
{
	out[0] = (in >> 0x00) & 0xFF;
	out[1] = (in >> 0x08) & 0xFF;
	out[2] = (in >> 0x10) & 0xFF;
	out[3] = (in >> 0x18) & 0xFF;
	out[4] = (in >> 0x20) & 0xFF;
	out[5] = (in >> 0x28) & 0xFF;
	out[6] = (in >> 0x30) & 0xFF;
	out[7] = (in >> 0x38) & 0xFF;
}

static inline uint64_t load8(const unsigned char * in)
{
	int i;
	uint64_t ret = in[7];

	for (i = 6; i >= 0; i--)
	{
		ret <<= 8;
		ret |= in[i];
	}

	return ret;
}

#endif