// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/******************************************************************************
 *   Copyright (C) 2009-2016, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *******************************************************************************
 */
#include "unicode/utypes.h"

#if U_PLATFORM_HAS_WIN32_API
#   define VC_EXTRALEAN
#   define WIN32_LEAN_AND_MEAN
#   define NOUSER
#   define NOSERVICE
#   define NOIME
#   define NOMCX
#include <windows.h>
#include <time.h>
#   ifdef __GNUC__
#       define WINDOWS_WITH_GNUC
#   endif
#endif

#if U_PLATFORM_IS_LINUX_BASED && U_HAVE_ELF_H
#   define U_ELF
#endif

#ifdef U_ELF
#   include <elf.h>
#   if defined(ELFCLASS64)
#       define U_ELF64
#   endif
    /* Old elf.h headers may not have EM_X86_64, or have EM_X8664 instead. */
#   ifndef EM_X86_64
#       define EM_X86_64 62
#   endif
#   define ICU_ENTRY_OFFSET 0
#endif

#include <stdio.h>
#include <stdlib.h>
#include "unicode/putil.h"
#include "cmemory.h"
#include "cstring.h"
#include "filestrm.h"
#include "toolutil.h"
#include "unicode/uclean.h"
#include "uoptions.h"
#include "pkg_genc.h"
#include "filetools.h"
#include "charstr.h"
#include "unicode/errorcode.h"

#define MAX_COLUMN ((uint32_t)(0xFFFFFFFFU))

#define HEX_0X 0 /*  0x1234 */
#define HEX_0H 1 /*  01234h */

/* prototypes --------------------------------------------------------------- */
static void
getOutFilename(
    const char *inFilename,
    const char *destdir,
    char *outFilename,
    int32_t outFilenameCapacity,
    char *entryName,
    int32_t entryNameCapacity,
    const char *newSuffix,
    const char *optFilename);

static uint32_t
write8(FileStream *out, uint8_t byte, uint32_t column);

static uint32_t
write32(FileStream *out, uint32_t byte, uint32_t column);

#if U_PLATFORM == U_PF_OS400
static uint32_t
write8str(FileStream *out, uint8_t byte, uint32_t column);
#endif
/* -------------------------------------------------------------------------- */

/*
Creating Template Files for New Platforms

Let the cc compiler help you get started.
Compile this program
    const unsigned int x[5] = {1, 2, 0xdeadbeef, 0xffffffff, 16};
with the -S option to produce assembly output.

For example, this will generate array.s:
gcc -S array.c

This will produce a .s file that may look like this:

    .file   "array.c"
    .version        "01.01"
gcc2_compiled.:
    .globl x
    .section        .rodata
    .align 4
    .type    x,@object
    .size    x,20
x:
    .long   1
    .long   2
    .long   -559038737
    .long   -1
    .long   16
    .ident  "GCC: (GNU) 2.96 20000731 (Red Hat Linux 7.1 2.96-85)"

which gives a starting point that will compile, and can be transformed
to become the template, generally with some consulting of as docs and
some experimentation.

If you want ICU to automatically use this assembly, you should
specify "GENCCODE_ASSEMBLY=-a name" in the specific config/mh-* file,
where the name is the compiler or platform that you used in this
assemblyHeader data structure.
*/
static const struct AssemblyType {
    const char *name;
    const char *header;
    const char *beginLine;
    const char *footer;
    int8_t      hexType; /* HEX_0X or HEX_0h */
} assemblyHeader[] = {
    /* For gcc assemblers, the meaning of .align changes depending on the */
    /* hardware, so we use .balign 16 which always means 16 bytes. */
    /* https://sourceware.org/binutils/docs/as/Pseudo-Ops.html */
    {"gcc",
        ".globl %s\n"
        "\t.section .note.GNU-stack,\"\",%%progbits\n"
        "#ifdef __CET__\n"
        "# include <cet.h>\n"
        "#endif\n"
        "\t.section .rodata\n"
        "\t.balign 16\n"
        "#ifdef U_HIDE_DATA_SYMBOL\n"
        "\t.hidden %s\n"
        "#endif\n"
        "\t.type %s,%%object\n"
        "%s:\n\n",

        ".long ",".size %s, .-%s\n",HEX_0X
    },
    {"gcc-darwin",
        /*"\t.section __TEXT,__text,regular,pure_instructions\n"
        "\t.section __TEXT,__picsymbolstub1,symbol_stubs,pure_instructions,32\n"*/
        ".globl _%s\n"
        "#ifdef U_HIDE_DATA_SYMBOL\n"
        "\t.private_extern _%s\n"
        "#endif\n"
        "\t.data\n"
        "\t.const\n"
        "\t.balign 16\n"
        "_%s:\n\n",

        ".long ","",HEX_0X
    },
    {"gcc-cygwin",
        ".globl _%s\n"
        "\t.section .rodata\n"
        "\t.balign 16\n"
        "_%s:\n\n",

        ".long ","",HEX_0X
    },
    {"gcc-mingw64",
        ".globl %s\n"
        "\t.section .rodata\n"
        "\t.balign 16\n"
        "%s:\n\n",

        ".long ","",HEX_0X
    },
/* 16 bytes alignment. */
/* http://docs.oracle.com/cd/E19641-01/802-1947/802-1947.pdf */
    {"sun",
        "\t.section \".rodata\"\n"
        "\t.align   16\n"
        ".globl     %s\n"
        "%s:\n",

        ".word ","",HEX_0X
    },
/* 16 bytes alignment for sun-x86. */
/* http://docs.oracle.com/cd/E19963-01/html/821-1608/eoiyg.html */
    {"sun-x86",
        "Drodata.rodata:\n"
        "\t.type   Drodata.rodata,@object\n"
        "\t.size   Drodata.rodata,0\n"
        "\t.globl  %s\n"
        "\t.align  16\n" 
        "%s:\n",

        ".4byte ","",HEX_0X
    },
/* 1<<4 bit alignment for aix. */
/* http://pic.dhe.ibm.com/infocenter/aix/v6r1/index.jsp?topic=%2Fcom.ibm.aix.aixassem%2Fdoc%2Falangref%2Fidalangref_csect_pseudoop.htm */
    {"xlc",
        ".globl %s{RO}\n"
        "\t.toc\n"
        "%s:\n"
        "\t.csect %s{RO}, 4\n",

        ".long ","",HEX_0X
    },
    {"aCC-ia64",
        "\t.file   \"%s.s\"\n"
        "\t.type   %s,@object\n"
        "\t.global %s\n"
        "\t.secalias .abe$0.rodata, \".rodata\"\n"
        "\t.section .abe$0.rodata = \"a\", \"progbits\"\n"
        "\t.align  16\n"
        "%s::\t",

        "data4 ","",HEX_0X
    },
    {"aCC-parisc",
        "\t.SPACE  $TEXT$\n"
        "\t.SUBSPA $LIT$\n"
        "%s\n"
        "\t.EXPORT %s\n"
        "\t.ALIGN  16\n",

        ".WORD ","",HEX_0X
    },
/* align 16 bytes */
/*  http://msdn.microsoft.com/en-us/library/dwa9fwef.aspx */
    { "masm",
      "\tTITLE %s\n"
      "; generated by genccode\n"
      ".386\n"
      ".model flat\n"
      "\tPUBLIC _%s\n"
      "ICUDATA_%s\tSEGMENT READONLY PARA PUBLIC FLAT 'DATA'\n"
      "\tALIGN 16\n"
      "_%s\tLABEL DWORD\n",
      "\tDWORD ","\nICUDATA_%s\tENDS\n\tEND\n",HEX_0H
    }
};

static int32_t assemblyHeaderIndex = -1;
static int32_t hexType = HEX_0X;

U_CAPI UBool U_EXPORT2
checkAssemblyHeaderName(const char* optAssembly) {
    int32_t idx;
    assemblyHeaderIndex = -1;
    for (idx = 0; idx < UPRV_LENGTHOF(assemblyHeader); idx++) {
        if (uprv_strcmp(optAssembly, assemblyHeader[idx].name) == 0) {
            assemblyHeaderIndex = idx;
            hexType = assemblyHeader[idx].hexType; /* set the hex type */
            return TRUE;
        }
    }

    return FALSE;
}


U_CAPI void U_EXPORT2
printAssemblyHeadersToStdErr(void) {
    int32_t idx;
    fprintf(stderr, "%s", assemblyHeader[0].name);
    for (idx = 1; idx < UPRV_LENGTHOF(assemblyHeader); idx++) {
        fprintf(stderr, ", %s", assemblyHeader[idx].name);
    }
    fprintf(stderr,
        ")\n");
}

U_CAPI void U_EXPORT2
writeAssemblyCode(
        const char *filename,
        const char *destdir,
        const char *optEntryPoint,
        const char *optFilename,
        char *outFilePath,
        size_t outFilePathCapacity) {
    uint32_t column = MAX_COLUMN;
    char entry[96];
    union {
        uint32_t uint32s[1024];
        char chars[4096];
    } buffer;
    FileStream *in, *out;
    size_t i, length, count;

    in=T_FileStream_open(filename, "rb");
    if(in==NULL) {
        fprintf(stderr, "genccode: unable to open input file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }

    getOutFilename(
        filename,
        destdir,
        buffer.chars,
        sizeof(buffer.chars),
        entry,
        sizeof(entry),
        ".S",
        optFilename);
    out=T_FileStream_open(buffer.chars, "w");
    if(out==NULL) {
        fprintf(stderr, "genccode: unable to open output file %s\n", buffer.chars);
        exit(U_FILE_ACCESS_ERROR);
    }

    if (outFilePath != NULL) {
        if (uprv_strlen(buffer.chars) >= outFilePathCapacity) {
            fprintf(stderr, "genccode: filename too long\n");
            exit(U_ILLEGAL_ARGUMENT_ERROR);
        }
        uprv_strcpy(outFilePath, buffer.chars);
    }

#if defined (WINDOWS_WITH_GNUC) && U_PLATFORM != U_PF_CYGWIN
    /* Need to fix the file separator character when using MinGW. */
    swapFileSepChar(outFilePath, U_FILE_SEP_CHAR, '/');
#endif

    if(optEntryPoint != NULL) {
        uprv_strcpy(entry, optEntryPoint);
        uprv_strcat(entry, "_dat");
    }

    /* turn dashes or dots in the entry name into underscores */
    length=uprv_strlen(entry);
    for(i=0; i<length; ++i) {
        if(entry[i]=='-' || entry[i]=='.') {
            entry[i]='_';
        }
    }

    count = snprintf(
        buffer.chars, sizeof(buffer.chars),
        assemblyHeader[assemblyHeaderIndex].header,
        entry, entry, entry, entry,
        entry, entry, entry, entry);
    if (count >= sizeof(buffer.chars)) {
        fprintf(stderr, "genccode: entry name too long (long filename?)\n");
        exit(U_ILLEGAL_ARGUMENT_ERROR);
    }
    T_FileStream_writeLine(out, buffer.chars);
    T_FileStream_writeLine(out, assemblyHeader[assemblyHeaderIndex].beginLine);

    for(;;) {
        memset(buffer.uint32s, 0, sizeof(buffer.uint32s));
        length=T_FileStream_read(in, buffer.uint32s, sizeof(buffer.uint32s));
        if(length==0) {
            break;
        }
        for(i=0; i<(length/sizeof(buffer.uint32s[0])); i++) {
            // TODO: What if the last read sees length not as a multiple of 4?
            column = write32(out, buffer.uint32s[i], column);
        }
    }

    T_FileStream_writeLine(out, "\n");

    count = snprintf(
        buffer.chars, sizeof(buffer.chars),
        assemblyHeader[assemblyHeaderIndex].footer,
        entry, entry, entry, entry,
        entry, entry, entry, entry);
    if (count >= sizeof(buffer.chars)) {
        fprintf(stderr, "genccode: entry name too long (long filename?)\n");
        exit(U_ILLEGAL_ARGUMENT_ERROR);
    }
    T_FileStream_writeLine(out, buffer.chars);

    if(T_FileStream_error(in)) {
        fprintf(stderr, "genccode: file read error while generating from file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }

    if(T_FileStream_error(out)) {
        fprintf(stderr, "genccode: file write error while generating from file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }

    T_FileStream_close(out);
    T_FileStream_close(in);
}

U_CAPI void U_EXPORT2
writeCCode(
        const char *filename,
        const char *destdir,
        const char *optName,
        const char *optFilename,
        char *outFilePath,
        size_t outFilePathCapacity) {
    uint32_t column = MAX_COLUMN;
    char buffer[4096], entry[96];
    FileStream *in, *out;
    size_t i, length, count;

    in=T_FileStream_open(filename, "rb");
    if(in==NULL) {
        fprintf(stderr, "genccode: unable to open input file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }

    if(optName != NULL) { /* prepend  'icudt28_' */
        // +2 includes the _ and the NUL
        if (uprv_strlen(optName) + 2 > sizeof(entry)) {
            fprintf(stderr, "genccode: entry name too long (long filename?)\n");
            exit(U_ILLEGAL_ARGUMENT_ERROR);
        }
        strcpy(entry, optName);
        strcat(entry, "_");
    } else {
        entry[0] = 0;
    }

    getOutFilename(
        filename,
        destdir,
        buffer,
        static_cast<int32_t>(sizeof(buffer)),
        entry + uprv_strlen(entry),
        static_cast<int32_t>(sizeof(entry) - uprv_strlen(entry)),
        ".c",
        optFilename);

    if (outFilePath != NULL) {
        if (uprv_strlen(buffer) >= outFilePathCapacity) {
            fprintf(stderr, "genccode: filename too long\n");
            exit(U_ILLEGAL_ARGUMENT_ERROR);
        }
        uprv_strcpy(outFilePath, buffer);
    }

    out=T_FileStream_open(buffer, "w");
    if(out==NULL) {
        fprintf(stderr, "genccode: unable to open output file %s\n", buffer);
        exit(U_FILE_ACCESS_ERROR);
    }

    /* turn dashes or dots in the entry name into underscores */
    length=uprv_strlen(entry);
    for(i=0; i<length; ++i) {
        if(entry[i]=='-' || entry[i]=='.') {
            entry[i]='_';
        }
    }

#if U_PLATFORM == U_PF_OS400
    /*
    TODO: Fix this once the compiler implements this feature. Keep in sync with udatamem.c

    This is here because this platform can't currently put
    const data into the read-only pages of an object or
    shared library (service program). Only strings are allowed in read-only
    pages, so we use char * strings to store the data.

    In order to prevent the beginning of the data from ever matching the
    magic numbers we must still use the initial double.
    [grhoten 4/24/2003]
    */
    count = snprintf(buffer, sizeof(buffer),
        "#ifndef IN_GENERATED_CCODE\n"
        "#define IN_GENERATED_CCODE\n"
        "#define U_DISABLE_RENAMING 1\n"
        "#include \"unicode/umachine.h\"\n"
        "#endif\n"
        "U_CDECL_BEGIN\n"
        "const struct {\n"
        "    double bogus;\n"
        "    const char *bytes; \n"
        "} %s={ 0.0, \n",
        entry);
    if (count >= sizeof(buffer)) {
        fprintf(stderr, "genccode: entry name too long (long filename?)\n");
        exit(U_ILLEGAL_ARGUMENT_ERROR);
    }
    T_FileStream_writeLine(out, buffer);

    for(;;) {
        length=T_FileStream_read(in, buffer, sizeof(buffer));
        if(length==0) {
            break;
        }
        for(i=0; i<length; ++i) {
            column = write8str(out, (uint8_t)buffer[i], column);
        }
    }

    T_FileStream_writeLine(out, "\"\n};\nU_CDECL_END\n");
#else
    /* Function renaming shouldn't be done in data */
    count = snprintf(buffer, sizeof(buffer),
        "#ifndef IN_GENERATED_CCODE\n"
        "#define IN_GENERATED_CCODE\n"
        "#define U_DISABLE_RENAMING 1\n"
        "#include \"unicode/umachine.h\"\n"
        "#endif\n"
        "U_CDECL_BEGIN\n"
        "const struct {\n"
        "    double bogus;\n"
        "    uint8_t bytes[%ld]; \n"
        "} %s={ 0.0, {\n",
        (long)T_FileStream_size(in), entry);
    if (count >= sizeof(buffer)) {
        fprintf(stderr, "genccode: entry name too long (long filename?)\n");
        exit(U_ILLEGAL_ARGUMENT_ERROR);
    }
    T_FileStream_writeLine(out, buffer);

    for(;;) {
        length=T_FileStream_read(in, buffer, sizeof(buffer));
        if(length==0) {
            break;
        }
        for(i=0; i<length; ++i) {
            column = write8(out, (uint8_t)buffer[i], column);
        }
    }

    T_FileStream_writeLine(out, "\n}\n};\nU_CDECL_END\n");
#endif

    if(T_FileStream_error(in)) {
        fprintf(stderr, "genccode: file read error while generating from file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }

    if(T_FileStream_error(out)) {
        fprintf(stderr, "genccode: file write error while generating from file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }

    T_FileStream_close(out);
    T_FileStream_close(in);
}

static uint32_t
write32(FileStream *out, uint32_t bitField, uint32_t column) {
    int32_t i;
    char bitFieldStr[64]; /* This is more bits than needed for a 32-bit number */
    char *s = bitFieldStr;
    uint8_t *ptrIdx = (uint8_t *)&bitField;
    static const char hexToStr[16] = {
        '0','1','2','3',
        '4','5','6','7',
        '8','9','A','B',
        'C','D','E','F'
    };

    /* write the value, possibly with comma and newline */
    if(column==MAX_COLUMN) {
        /* first byte */
        column=1;
    } else if(column<32) {
        *(s++)=',';
        ++column;
    } else {
        *(s++)='\n';
        uprv_strcpy(s, assemblyHeader[assemblyHeaderIndex].beginLine);
        s+=uprv_strlen(s);
        column=1;
    }

    if (bitField < 10) {
        /* It's a small number. Don't waste the space for 0x */
        *(s++)=hexToStr[bitField];
    }
    else {
        int seenNonZero = 0; /* This is used to remove leading zeros */

        if(hexType==HEX_0X) {
         *(s++)='0';
         *(s++)='x';
        } else if(hexType==HEX_0H) {
         *(s++)='0';
        }

        /* This creates a 32-bit field */
#if U_IS_BIG_ENDIAN
        for (i = 0; i < sizeof(uint32_t); i++)
#else
        for (i = sizeof(uint32_t)-1; i >= 0 ; i--)
#endif
        {
            uint8_t value = ptrIdx[i];
            if (value || seenNonZero) {
                *(s++)=hexToStr[value>>4];
                *(s++)=hexToStr[value&0xF];
                seenNonZero = 1;
            }
        }
        if(hexType==HEX_0H) {
         *(s++)='h';
        }
    }

    *(s++)=0;
    T_FileStream_writeLine(out, bitFieldStr);
    return column;
}

static uint32_t
write8(FileStream *out, uint8_t byte, uint32_t column) {
    char s[4];
    int i=0;

    /* convert the byte value to a string */
    if(byte>=100) {
        s[i++]=(char)('0'+byte/100);
        byte%=100;
    }
    if(i>0 || byte>=10) {
        s[i++]=(char)('0'+byte/10);
        byte%=10;
    }
    s[i++]=(char)('0'+byte);
    s[i]=0;

    /* write the value, possibly with comma and newline */
    if(column==MAX_COLUMN) {
        /* first byte */
        column=1;
    } else if(column<16) {
        T_FileStream_writeLine(out, ",");
        ++column;
    } else {
        T_FileStream_writeLine(out, ",\n");
        column=1;
    }
    T_FileStream_writeLine(out, s);
    return column;
}

#if U_PLATFORM == U_PF_OS400
static uint32_t
write8str(FileStream *out, uint8_t byte, uint32_t column) {
    char s[8];

    if (byte > 7)
        sprintf(s, "\\x%X", byte);
    else
        sprintf(s, "\\%X", byte);

    /* write the value, possibly with comma and newline */
    if(column==MAX_COLUMN) {
        /* first byte */
        column=1;
        T_FileStream_writeLine(out, "\"");
    } else if(column<24) {
        ++column;
    } else {
        T_FileStream_writeLine(out, "\"\n\"");
        column=1;
    }
    T_FileStream_writeLine(out, s);
    return column;
}
#endif

static void
getOutFilename(
        const char *inFilename,
        const char *destdir,
        char *outFilename,
        int32_t outFilenameCapacity,
        char *entryName,
        int32_t entryNameCapacity,
        const char *newSuffix,
        const char *optFilename) {
    const char *basename=findBasename(inFilename), *suffix=uprv_strrchr(basename, '.');

    icu::CharString outFilenameBuilder;
    icu::CharString entryNameBuilder;
    icu::ErrorCode status;

    /* copy path */
    if(destdir!=NULL && *destdir!=0) {
        outFilenameBuilder.append(destdir, status);
        outFilenameBuilder.ensureEndsWithFileSeparator(status);
    } else {
        outFilenameBuilder.append(inFilename, static_cast<int32_t>(basename - inFilename), status);
    }
    inFilename=basename;

    if(suffix==NULL) {
        /* the filename does not have a suffix */
        entryNameBuilder.append(inFilename, status);
        if(optFilename != NULL) {
            outFilenameBuilder.append(optFilename, status);
        } else {
            outFilenameBuilder.append(inFilename, status);
        }
        outFilenameBuilder.append(newSuffix, status);
    } else {
        int32_t saveOutFilenameLength = outFilenameBuilder.length();
        /* copy basename */
        while(inFilename<suffix) {
            // iSeries cannot have '-' in the .o objects.
            char c = (*inFilename=='-') ? '_' : *inFilename;
            outFilenameBuilder.append(c, status);
            entryNameBuilder.append(c, status);
            inFilename++;
        }

        /* replace '.' by '_' */
        outFilenameBuilder.append('_', status);
        entryNameBuilder.append('_', status);
        ++inFilename;

        /* copy suffix */
        outFilenameBuilder.append(inFilename, status);
        entryNameBuilder.append(inFilename, status);

        if(optFilename != NULL) {
            outFilenameBuilder.truncate(saveOutFilenameLength);
            outFilenameBuilder.append(optFilename, status);
        }
        // add ".c"
        outFilenameBuilder.append(newSuffix, status);
    }

    if (status.isFailure()) {
        fprintf(stderr, "genccode: error building filename or entrypoint\n");
        exit(status.get());
    }

    if (outFilenameBuilder.length() >= outFilenameCapacity) {
        fprintf(stderr, "genccode: output filename too long\n");
        exit(U_ILLEGAL_ARGUMENT_ERROR);
    }

    if (entryNameBuilder.length() >= entryNameCapacity) {
        fprintf(stderr, "genccode: entry name too long (long filename?)\n");
        exit(U_ILLEGAL_ARGUMENT_ERROR);
    }

    outFilenameBuilder.extract(outFilename, outFilenameCapacity, status);
    entryNameBuilder.extract(entryName, entryNameCapacity, status);
}

#ifdef CAN_GENERATE_OBJECTS
static void
getArchitecture(uint16_t *pCPU, uint16_t *pBits, UBool *pIsBigEndian, const char *optMatchArch) {
    union {
        char        bytes[2048];
#ifdef U_ELF
        Elf32_Ehdr  header32;
        /* Elf32_Ehdr and ELF64_Ehdr are identical for the necessary fields. */
#elif U_PLATFORM_HAS_WIN32_API
        IMAGE_FILE_HEADER header;
#endif
    } buffer;

    const char *filename;
    FileStream *in;
    int32_t length;

#ifdef U_ELF

#elif U_PLATFORM_HAS_WIN32_API
    const IMAGE_FILE_HEADER *pHeader;
#else
#   error "Unknown platform for CAN_GENERATE_OBJECTS."
#endif

    if(optMatchArch != NULL) {
        filename=optMatchArch;
    } else {
        /* set defaults */
#ifdef U_ELF
        /* set EM_386 because elf.h does not provide better defaults */
        *pCPU=EM_386;
        *pBits=32;
        *pIsBigEndian=(UBool)(U_IS_BIG_ENDIAN ? ELFDATA2MSB : ELFDATA2LSB);
#elif U_PLATFORM_HAS_WIN32_API
        // Windows always runs in little-endian mode.
        *pIsBigEndian = FALSE;

        // Note: The various _M_<arch> macros are predefined by the MSVC compiler based
        // on the target compilation architecture.
        // https://docs.microsoft.com/cpp/preprocessor/predefined-macros

        // link.exe will link an IMAGE_FILE_MACHINE_UNKNOWN data-only .obj file
        // no matter what architecture it is targeting (though other values are
        // required to match). Unfortunately, the variable name decoration/mangling
        // is slightly different on x86, which means we can't use the UNKNOWN type
        // for all architectures though.
#   if defined(_M_IX86)
        *pCPU = IMAGE_FILE_MACHINE_I386;
#   else
        *pCPU = IMAGE_FILE_MACHINE_UNKNOWN;
#   endif
#   if defined(_M_IA64) || defined(_M_AMD64) || defined (_M_ARM64)
        *pBits = 64; // Doesn't seem to be used for anything interesting though?
#   elif defined(_M_IX86) || defined(_M_ARM)
        *pBits = 32;
#   else
#      error "Unknown platform for CAN_GENERATE_OBJECTS."
#   endif
#else
#   error "Unknown platform for CAN_GENERATE_OBJECTS."
#endif
        return;
    }

    in=T_FileStream_open(filename, "rb");
    if(in==NULL) {
        fprintf(stderr, "genccode: unable to open match-arch file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }
    length=T_FileStream_read(in, buffer.bytes, sizeof(buffer.bytes));

#ifdef U_ELF
    if(length<(int32_t)sizeof(Elf32_Ehdr)) {
        fprintf(stderr, "genccode: match-arch file %s is too short\n", filename);
        exit(U_UNSUPPORTED_ERROR);
    }
    if(
        buffer.header32.e_ident[0]!=ELFMAG0 ||
        buffer.header32.e_ident[1]!=ELFMAG1 ||
        buffer.header32.e_ident[2]!=ELFMAG2 ||
        buffer.header32.e_ident[3]!=ELFMAG3 ||
        buffer.header32.e_ident[EI_CLASS]<ELFCLASS32 || buffer.header32.e_ident[EI_CLASS]>ELFCLASS64
    ) {
        fprintf(stderr, "genccode: match-arch file %s is not an ELF object file, or not supported\n", filename);
        exit(U_UNSUPPORTED_ERROR);
    }

    *pBits= buffer.header32.e_ident[EI_CLASS]==ELFCLASS32 ? 32 : 64; /* only 32 or 64: see check above */
#ifdef U_ELF64
    if(*pBits!=32 && *pBits!=64) {
        fprintf(stderr, "genccode: currently only supports 32-bit and 64-bit ELF format\n");
        exit(U_UNSUPPORTED_ERROR);
    }
#else
    if(*pBits!=32) {
        fprintf(stderr, "genccode: built with elf.h missing 64-bit definitions\n");
        exit(U_UNSUPPORTED_ERROR);
    }
#endif

    *pIsBigEndian=(UBool)(buffer.header32.e_ident[EI_DATA]==ELFDATA2MSB);
    if(*pIsBigEndian!=U_IS_BIG_ENDIAN) {
        fprintf(stderr, "genccode: currently only same-endianness ELF formats are supported\n");
        exit(U_UNSUPPORTED_ERROR);
    }
    /* TODO: Support byte swapping */

    *pCPU=buffer.header32.e_machine;
#elif U_PLATFORM_HAS_WIN32_API
    if(length<sizeof(IMAGE_FILE_HEADER)) {
        fprintf(stderr, "genccode: match-arch file %s is too short\n", filename);
        exit(U_UNSUPPORTED_ERROR);
    }
    /* TODO: Use buffer.header.  Keep aliasing legal.  */
    pHeader=(const IMAGE_FILE_HEADER *)buffer.bytes;
    *pCPU=pHeader->Machine;
    /*
     * The number of bits is implicit with the Machine value.
     * *pBits is ignored in the calling code, so this need not be precise.
     */
    *pBits= *pCPU==IMAGE_FILE_MACHINE_I386 ? 32 : 64;
    /* Windows always runs on little-endian CPUs. */
    *pIsBigEndian=FALSE;
#else
#   error "Unknown platform for CAN_GENERATE_OBJECTS."
#endif

    T_FileStream_close(in);
}

U_CAPI void U_EXPORT2
writeObjectCode(
        const char *filename,
        const char *destdir,
        const char *optEntryPoint,
        const char *optMatchArch,
        const char *optFilename,
        char *outFilePath,
        size_t outFilePathCapacity,
        UBool optWinDllExport) {
    /* common variables */
    char buffer[4096], entry[96]={ 0 };
    FileStream *in, *out;
    const char *newSuffix;
    int32_t i, entryLength, length, size, entryOffset=0, entryLengthOffset=0;

    uint16_t cpu, bits;
    UBool makeBigEndian;

    (void)optWinDllExport; /* unused except Windows */

    /* platform-specific variables and initialization code */
#ifdef U_ELF
    /* 32-bit Elf file header */
    static Elf32_Ehdr header32={
        {
            /* e_ident[] */
            ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
            ELFCLASS32,
            U_IS_BIG_ENDIAN ? ELFDATA2MSB : ELFDATA2LSB,
            EV_CURRENT /* EI_VERSION */
        },
        ET_REL,
        EM_386,
        EV_CURRENT, /* e_version */
        0, /* e_entry */
        0, /* e_phoff */
        (Elf32_Off)sizeof(Elf32_Ehdr), /* e_shoff */
        0, /* e_flags */
        (Elf32_Half)sizeof(Elf32_Ehdr), /* eh_size */
        0, /* e_phentsize */
        0, /* e_phnum */
        (Elf32_Half)sizeof(Elf32_Shdr), /* e_shentsize */
        5, /* e_shnum */
        2 /* e_shstrndx */
    };

    /* 32-bit Elf section header table */
    static Elf32_Shdr sectionHeaders32[5]={
        { /* SHN_UNDEF */
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0
        },
        { /* .symtab */
            1, /* sh_name */
            SHT_SYMTAB,
            0, /* sh_flags */
            0, /* sh_addr */
            (Elf32_Off)(sizeof(header32)+sizeof(sectionHeaders32)), /* sh_offset */
            (Elf32_Word)(2*sizeof(Elf32_Sym)), /* sh_size */
            3, /* sh_link=sect hdr index of .strtab */
            1, /* sh_info=One greater than the symbol table index of the last
                * local symbol (with STB_LOCAL). */
            4, /* sh_addralign */
            (Elf32_Word)(sizeof(Elf32_Sym)) /* sh_entsize */
        },
        { /* .shstrtab */
            9, /* sh_name */
            SHT_STRTAB,
            0, /* sh_flags */
            0, /* sh_addr */
            (Elf32_Off)(sizeof(header32)+sizeof(sectionHeaders32)+2*sizeof(Elf32_Sym)), /* sh_offset */
            40, /* sh_size */
            0, /* sh_link */
            0, /* sh_info */
            1, /* sh_addralign */
            0 /* sh_entsize */
        },
        { /* .strtab */
            19, /* sh_name */
            SHT_STRTAB,
            0, /* sh_flags */
            0, /* sh_addr */
            (Elf32_Off)(sizeof(header32)+sizeof(sectionHeaders32)+2*sizeof(Elf32_Sym)+40), /* sh_offset */
            (Elf32_Word)sizeof(entry), /* sh_size */
            0, /* sh_link */
            0, /* sh_info */
            1, /* sh_addralign */
            0 /* sh_entsize */
        },
        { /* .rodata */
            27, /* sh_name */
            SHT_PROGBITS,
            SHF_ALLOC, /* sh_flags */
            0, /* sh_addr */
            (Elf32_Off)(sizeof(header32)+sizeof(sectionHeaders32)+2*sizeof(Elf32_Sym)+40+sizeof(entry)), /* sh_offset */
            0, /* sh_size */
            0, /* sh_link */
            0, /* sh_info */
            16, /* sh_addralign */
            0 /* sh_entsize */
        }
    };

    /* symbol table */
    static Elf32_Sym symbols32[2]={
        { /* STN_UNDEF */
            0, 0, 0, 0, 0, 0
        },
        { /* data entry point */
            1, /* st_name */
            0, /* st_value */
            0, /* st_size */
            ELF64_ST_INFO(STB_GLOBAL, STT_OBJECT),
            0, /* st_other */
            4 /* st_shndx=index of related section table entry */
        }
    };

    /* section header string table, with decimal string offsets */
    static const char sectionStrings[40]=
        /*  0 */ "\0"
        /*  1 */ ".symtab\0"
        /*  9 */ ".shstrtab\0"
        /* 19 */ ".strtab\0"
        /* 27 */ ".rodata\0"
        /* 35 */ "\0\0\0\0"; /* contains terminating NUL */
        /* 40: padded to multiple of 8 bytes */

    /*
     * Use entry[] for the string table which will contain only the
     * entry point name.
     * entry[0] must be 0 (NUL)
     * The entry point name can be up to 38 characters long (sizeof(entry)-2).
     */

    /* 16-align .rodata in the .o file, just in case */
    static const char padding[16]={ 0 };
    int32_t paddingSize;

#ifdef U_ELF64
    /* 64-bit Elf file header */
    static Elf64_Ehdr header64={
        {
            /* e_ident[] */
            ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3,
            ELFCLASS64,
            U_IS_BIG_ENDIAN ? ELFDATA2MSB : ELFDATA2LSB,
            EV_CURRENT /* EI_VERSION */
        },
        ET_REL,
        EM_X86_64,
        EV_CURRENT, /* e_version */
        0, /* e_entry */
        0, /* e_phoff */
        (Elf64_Off)sizeof(Elf64_Ehdr), /* e_shoff */
        0, /* e_flags */
        (Elf64_Half)sizeof(Elf64_Ehdr), /* eh_size */
        0, /* e_phentsize */
        0, /* e_phnum */
        (Elf64_Half)sizeof(Elf64_Shdr), /* e_shentsize */
        5, /* e_shnum */
        2 /* e_shstrndx */
    };

    /* 64-bit Elf section header table */
    static Elf64_Shdr sectionHeaders64[5]={
        { /* SHN_UNDEF */
            0, 0, 0, 0, 0, 0, 0, 0, 0, 0
        },
        { /* .symtab */
            1, /* sh_name */
            SHT_SYMTAB,
            0, /* sh_flags */
            0, /* sh_addr */
            (Elf64_Off)(sizeof(header64)+sizeof(sectionHeaders64)), /* sh_offset */
            (Elf64_Xword)(2*sizeof(Elf64_Sym)), /* sh_size */
            3, /* sh_link=sect hdr index of .strtab */
            1, /* sh_info=One greater than the symbol table index of the last
                * local symbol (with STB_LOCAL). */
            4, /* sh_addralign */
            (Elf64_Xword)(sizeof(Elf64_Sym)) /* sh_entsize */
        },
        { /* .shstrtab */
            9, /* sh_name */
            SHT_STRTAB,
            0, /* sh_flags */
            0, /* sh_addr */
            (Elf64_Off)(sizeof(header64)+sizeof(sectionHeaders64)+2*sizeof(Elf64_Sym)), /* sh_offset */
            40, /* sh_size */
            0, /* sh_link */
            0, /* sh_info */
            1, /* sh_addralign */
            0 /* sh_entsize */
        },
        { /* .strtab */
            19, /* sh_name */
            SHT_STRTAB,
            0, /* sh_flags */
            0, /* sh_addr */
            (Elf64_Off)(sizeof(header64)+sizeof(sectionHeaders64)+2*sizeof(Elf64_Sym)+40), /* sh_offset */
            (Elf64_Xword)sizeof(entry), /* sh_size */
            0, /* sh_link */
            0, /* sh_info */
            1, /* sh_addralign */
            0 /* sh_entsize */
        },
        { /* .rodata */
            27, /* sh_name */
            SHT_PROGBITS,
            SHF_ALLOC, /* sh_flags */
            0, /* sh_addr */
            (Elf64_Off)(sizeof(header64)+sizeof(sectionHeaders64)+2*sizeof(Elf64_Sym)+40+sizeof(entry)), /* sh_offset */
            0, /* sh_size */
            0, /* sh_link */
            0, /* sh_info */
            16, /* sh_addralign */
            0 /* sh_entsize */
        }
    };

    /*
     * 64-bit symbol table
     * careful: different order of items compared with Elf32_sym!
     */
    static Elf64_Sym symbols64[2]={
        { /* STN_UNDEF */
            0, 0, 0, 0, 0, 0
        },
        { /* data entry point */
            1, /* st_name */
            ELF64_ST_INFO(STB_GLOBAL, STT_OBJECT),
            0, /* st_other */
            4, /* st_shndx=index of related section table entry */
            0, /* st_value */
            0 /* st_size */
        }
    };

#endif /* U_ELF64 */

    /* entry[] have a leading NUL */
    entryOffset=1;

    /* in the common code, count entryLength from after the NUL */
    entryLengthOffset=1;

    newSuffix=".o";

#elif U_PLATFORM_HAS_WIN32_API
    struct {
        IMAGE_FILE_HEADER fileHeader;
        IMAGE_SECTION_HEADER sections[2];
        char linkerOptions[100];
    } objHeader;
    IMAGE_SYMBOL symbols[1];
    struct {
        DWORD sizeofLongNames;
        char longNames[100];
    } symbolNames;

    /*
     * entry sometimes have a leading '_'
     * overwritten if entryOffset==0 depending on the target platform
     * see check for cpu below
     */
    entry[0]='_';

    newSuffix=".obj";
#else
#   error "Unknown platform for CAN_GENERATE_OBJECTS."
#endif

    /* deal with options, files and the entry point name */
    getArchitecture(&cpu, &bits, &makeBigEndian, optMatchArch);
    if (optMatchArch)
    {
        printf("genccode: --match-arch cpu=%hu bits=%hu big-endian=%d\n", cpu, bits, makeBigEndian);
    }
    else
    {
        printf("genccode: using architecture cpu=%hu bits=%hu big-endian=%d\n", cpu, bits, makeBigEndian);
    }
#if U_PLATFORM_HAS_WIN32_API
    if(cpu==IMAGE_FILE_MACHINE_I386) {
        entryOffset=1;
    }
#endif

    in=T_FileStream_open(filename, "rb");
    if(in==NULL) {
        fprintf(stderr, "genccode: unable to open input file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }
    size=T_FileStream_size(in);

    getOutFilename(
        filename,
        destdir,
        buffer,
        sizeof(buffer),
        entry + entryOffset,
        sizeof(entry) - entryOffset,
        newSuffix,
        optFilename);

    if (outFilePath != NULL) {
        if (uprv_strlen(buffer) >= outFilePathCapacity) {
            fprintf(stderr, "genccode: filename too long\n");
            exit(U_ILLEGAL_ARGUMENT_ERROR);
        }
        uprv_strcpy(outFilePath, buffer);
    }

    if(optEntryPoint != NULL) {
        uprv_strcpy(entry+entryOffset, optEntryPoint);
        uprv_strcat(entry+entryOffset, "_dat");
    }
    /* turn dashes in the entry name into underscores */
    entryLength=(int32_t)uprv_strlen(entry+entryLengthOffset);
    for(i=0; i<entryLength; ++i) {
        if(entry[entryLengthOffset+i]=='-') {
            entry[entryLengthOffset+i]='_';
        }
    }

    /* open the output file */
    out=T_FileStream_open(buffer, "wb");
    if(out==NULL) {
        fprintf(stderr, "genccode: unable to open output file %s\n", buffer);
        exit(U_FILE_ACCESS_ERROR);
    }

#ifdef U_ELF
    if(bits==32) {
        header32.e_ident[EI_DATA]= makeBigEndian ? ELFDATA2MSB : ELFDATA2LSB;
        header32.e_machine=cpu;

        /* 16-align .rodata in the .o file, just in case */
        paddingSize=sectionHeaders32[4].sh_offset & 0xf;
        if(paddingSize!=0) {
                paddingSize=0x10-paddingSize;
                sectionHeaders32[4].sh_offset+=paddingSize;
        }

        sectionHeaders32[4].sh_size=(Elf32_Word)size;

        symbols32[1].st_size=(Elf32_Word)size;

        /* write .o headers */
        T_FileStream_write(out, &header32, (int32_t)sizeof(header32));
        T_FileStream_write(out, sectionHeaders32, (int32_t)sizeof(sectionHeaders32));
        T_FileStream_write(out, symbols32, (int32_t)sizeof(symbols32));
    } else /* bits==64 */ {
#ifdef U_ELF64
        header64.e_ident[EI_DATA]= makeBigEndian ? ELFDATA2MSB : ELFDATA2LSB;
        header64.e_machine=cpu;

        /* 16-align .rodata in the .o file, just in case */
        paddingSize=sectionHeaders64[4].sh_offset & 0xf;
        if(paddingSize!=0) {
                paddingSize=0x10-paddingSize;
                sectionHeaders64[4].sh_offset+=paddingSize;
        }

        sectionHeaders64[4].sh_size=(Elf64_Xword)size;

        symbols64[1].st_size=(Elf64_Xword)size;

        /* write .o headers */
        T_FileStream_write(out, &header64, (int32_t)sizeof(header64));
        T_FileStream_write(out, sectionHeaders64, (int32_t)sizeof(sectionHeaders64));
        T_FileStream_write(out, symbols64, (int32_t)sizeof(symbols64));
#endif
    }

    T_FileStream_write(out, sectionStrings, (int32_t)sizeof(sectionStrings));
    T_FileStream_write(out, entry, (int32_t)sizeof(entry));
    if(paddingSize!=0) {
        T_FileStream_write(out, padding, paddingSize);
    }
#elif U_PLATFORM_HAS_WIN32_API
    /* populate the .obj headers */
    uprv_memset(&objHeader, 0, sizeof(objHeader));
    uprv_memset(&symbols, 0, sizeof(symbols));
    uprv_memset(&symbolNames, 0, sizeof(symbolNames));

    /* write the linker export directive */
    if (optWinDllExport) {
        uprv_strcpy(objHeader.linkerOptions, "-export:");
        length=8;
        uprv_strcpy(objHeader.linkerOptions+length, entry);
        length+=entryLength;
        uprv_strcpy(objHeader.linkerOptions+length, ",data ");
        length+=6;
    }
    else {
        length=0;
    }

    /* set the file header */
    objHeader.fileHeader.Machine=cpu;
    objHeader.fileHeader.NumberOfSections=2;
    objHeader.fileHeader.TimeDateStamp=(DWORD)time(NULL);
    objHeader.fileHeader.PointerToSymbolTable=IMAGE_SIZEOF_FILE_HEADER+2*IMAGE_SIZEOF_SECTION_HEADER+length+size; /* start of symbol table */
    objHeader.fileHeader.NumberOfSymbols=1;

    /* set the section for the linker options */
    uprv_strncpy((char *)objHeader.sections[0].Name, ".drectve", 8);
    objHeader.sections[0].SizeOfRawData=length;
    objHeader.sections[0].PointerToRawData=IMAGE_SIZEOF_FILE_HEADER+2*IMAGE_SIZEOF_SECTION_HEADER;
    objHeader.sections[0].Characteristics=IMAGE_SCN_LNK_INFO|IMAGE_SCN_LNK_REMOVE|IMAGE_SCN_ALIGN_1BYTES;

    /* set the data section */
    uprv_strncpy((char *)objHeader.sections[1].Name, ".rdata", 6);
    objHeader.sections[1].SizeOfRawData=size;
    objHeader.sections[1].PointerToRawData=IMAGE_SIZEOF_FILE_HEADER+2*IMAGE_SIZEOF_SECTION_HEADER+length;
    objHeader.sections[1].Characteristics=IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_ALIGN_16BYTES|IMAGE_SCN_MEM_READ;

    /* set the symbol table */
    if(entryLength<=8) {
        uprv_strncpy((char *)symbols[0].N.ShortName, entry, entryLength);
        symbolNames.sizeofLongNames=4;
    } else {
        symbols[0].N.Name.Short=0;
        symbols[0].N.Name.Long=4;
        symbolNames.sizeofLongNames=4+entryLength+1;
        uprv_strcpy(symbolNames.longNames, entry);
    }
    symbols[0].SectionNumber=2;
    symbols[0].StorageClass=IMAGE_SYM_CLASS_EXTERNAL;

    /* write the file header and the linker options section */
    T_FileStream_write(out, &objHeader, objHeader.sections[1].PointerToRawData);
#else
#   error "Unknown platform for CAN_GENERATE_OBJECTS."
#endif

    /* copy the data file into section 2 */
    for(;;) {
        length=T_FileStream_read(in, buffer, sizeof(buffer));
        if(length==0) {
            break;
        }
        T_FileStream_write(out, buffer, (int32_t)length);
    }

#if U_PLATFORM_HAS_WIN32_API
    /* write the symbol table */
    T_FileStream_write(out, symbols, IMAGE_SIZEOF_SYMBOL);
    T_FileStream_write(out, &symbolNames, symbolNames.sizeofLongNames);
#endif

    if(T_FileStream_error(in)) {
        fprintf(stderr, "genccode: file read error while generating from file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }

    if(T_FileStream_error(out)) {
        fprintf(stderr, "genccode: file write error while generating from file %s\n", filename);
        exit(U_FILE_ACCESS_ERROR);
    }

    T_FileStream_close(out);
    T_FileStream_close(in);
}
#endif