/**
 * @file decaf/common.h
 * @author Mike Hamburg
 *
 * @copyright
 *   Copyright (c) 2015 Cryptography Research, Inc.  \n
 *   Released under the MIT License.  See LICENSE.txt for license information.
 *
 * @brief Common utility headers for Decaf library.
 */

#ifndef __DECAF_COMMON_H__
#define __DECAF_COMMON_H__ 1

#include <stdint.h>
#include <sys/types.h>
#include <openssl/e_os2.h>

#ifdef __cplusplus
extern "C" {
#endif

/* Internal word types.
 *
 * Somewhat tricky.  This could be decided separately per platform.  However,
 * the structs do need to be all the same size and alignment on a given
 * platform to support dynamic linking, since even if you header was built
 * with eg arch_neon, you might end up linking a library built with arch_arm32.
 */
#ifndef DECAF_WORD_BITS
    #if (defined(__ILP64__) || defined(__amd64__) || defined(__x86_64__) || (((__UINT_FAST32_MAX__)>>30)>>30))
        #define DECAF_WORD_BITS 64 /**< The number of bits in a word */
    #else
        #define DECAF_WORD_BITS 32 /**< The number of bits in a word */
    #endif
#endif
    
#if DECAF_WORD_BITS == 64
typedef uint64_t decaf_word_t;      /**< Word size for internal computations */
typedef int64_t decaf_sword_t;      /**< Signed word size for internal computations */
typedef uint64_t decaf_bool_t;      /**< "Boolean" type, will be set to all-zero or all-one (i.e. -1u) */
typedef __uint128_t decaf_dword_t;  /**< Double-word size for internal computations */
typedef __int128_t decaf_dsword_t;  /**< Signed double-word size for internal computations */
#elif DECAF_WORD_BITS == 32         /**< The number of bits in a word */
typedef uint32_t decaf_word_t;      /**< Word size for internal computations */
typedef int32_t decaf_sword_t;      /**< Signed word size for internal computations */
typedef uint32_t decaf_bool_t;      /**< "Boolean" type, will be set to all-zero or all-one (i.e. -1u) */
typedef uint64_t decaf_dword_t;     /**< Double-word size for internal computations */
typedef int64_t decaf_dsword_t;     /**< Signed double-word size for internal computations */
#else
#error "Only supporting DECAF_WORD_BITS = 32 or 64 for now"
#endif
    
/** DECAF_TRUE = -1 so that DECAF_TRUE & x = x */
static const decaf_bool_t DECAF_TRUE = -(decaf_bool_t)1;

/** DECAF_FALSE = 0 so that DECAF_FALSE & x = 0 */
static const decaf_bool_t DECAF_FALSE = 0;

/** Another boolean type used to indicate success or failure. */
typedef enum {
    DECAF_SUCCESS = -1, /**< The operation succeeded. */
    DECAF_FAILURE = 0   /**< The operation failed. */
} decaf_error_t;


/** Return success if x is true */
static ossl_inline decaf_error_t
decaf_succeed_if(decaf_bool_t x) {
    return (decaf_error_t)x;
}

/** Return DECAF_TRUE iff x == DECAF_SUCCESS */
static ossl_inline decaf_bool_t
decaf_successful(decaf_error_t e) {
    decaf_dword_t w = ((decaf_word_t)e) ^  ((decaf_word_t)DECAF_SUCCESS);
    return (w-1)>>DECAF_WORD_BITS;
}
    
#ifdef __cplusplus
} /* extern "C" */
#endif
    
#endif /* __DECAF_COMMON_H__ */