#ifndef FUNCCRYPT_H
#define FUNCCRYPT_H 1

#include <stdlib.h>
#include <stdint.h>

#if !defined(__GNUC__) || !defined(__GNUC_MINOR__)
#error "This is only verified to work with a GCC compiler!"
#endif

/* Force GCC struct for MingW compilers and pack them,
 * which means the struct is 1-byte aligned.
 */
#define GCC_PACKED __attribute__((packed, gcc_struct))

typedef struct crypt_header {
    uint64_t key;
    uint8_t crpyted;
    uint32_t marker;
    uint64_t func_body[0];
} GCC_PACKED crypt_header;

typedef enum crypt_return {
    CRET_ERROR    /* Neither prologue marker nor epilogue marker found. */,
    CRET_PROLOGUE /* prologue marker found */,
    CRET_EPILOGUE /* epilogue marker found */,
    CRET_CHECK    /* all pre (en|de)cryption checks successful */,
    CRET_OK       /* (en|de)cryption succeeded */
} crypt_return;

#define CRYPT_FUNC_MAXSIZ 0x100
#define CRYPT_FUNC(fn) \
    crypt_func((void *)fn)
#define CRYPT_PROLOGUE(fn) \
    crypt_return __cr; \
    { \
        __cr = CRYPT_FUNC(fn); \
        if (__cr != CRET_OK) \
            asm volatile goto("jmp %l0          \n" \
                : : : : cr_epilogue); \
        asm volatile goto("jmp %l0          \n" \
            : : : : cr_prologue); \
        asm volatile( \
            ".byte " \
            /* key: */     "0x00, 0x00, 0x00, 0x00," \
                           "0x00, 0x00, 0x00, 0x00," \
            /* crypted: */ "0x00," \
            /* marker: */  "0xDE, 0xC0, 0xDE, 0xC0;  \n" \
        ); \
    } \
    cr_prologue: {
#define CRYPT_EPILOGUE(fn) \
    } { \
        asm volatile goto("jmp %l0          \n" \
            : : : : cr_epilogue); \
        asm volatile( \
            ".byte " \
            /* Insert encryption pad, so we can find the end marker,
             * while the function body is encrypted.
             * (XOR 64 bit encryption == 8 byte)
             */ \
            "0x00, 0x00, 0x00, 0x00," \
            "0x00, 0x00, 0x00, 0x00," \
            /* marker: */   "0xFE, 0xCA, 0xFE, 0xCA;  \n" \
        ); \
    } \
    cr_epilogue: \
    CRYPT_FUNC(fn);

#define CRYPT_FNDEF(name, ...) \
    void name( __VA_ARGS__ ) { \
        CRYPT_PROLOGUE( name );
#define CRYPT_FNEND(name) \
        CRYPT_EPILOGUE(name); \
    }

extern const char *crypt_strs[];
extern void printHexBuf(uint8_t *buf, size_t siz, size_t chars_per_line);
extern crypt_return crypt_func(void *fn_start);

#endif