/******************************************************************************
 *   Copyright (C) 2009-2010, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *******************************************************************************
 */
#include "unicode/utypes.h"

#ifdef U_WINDOWS
#   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

#ifdef U_LINUX
#   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"

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

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

#if defined(U_WINDOWS) || defined(U_ELF)
#define CAN_GENERATE_OBJECTS
#endif

/* prototypes --------------------------------------------------------------- */
static void
getOutFilename(const char *inFilename, const char *destdir, char *outFilename, char *entryName, 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);

#ifdef 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[] = {
    {"gcc",
        ".globl %s\n"
        "\t.section .note.GNU-stack,\"\",%%progbits\n"
        "\t.section .rodata\n"
        "\t.align 8\n" /* Either align 8 bytes or 2^8 (256) bytes. 8 bytes is needed. */
        "\t.type %s,%%object\n"
        "%s:\n\n",

        ".long ","",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"
        "\t.data\n"
        "\t.const\n"
        "\t.align 4\n"  /* 1<<4 = 16 */
        "_%s:\n\n",

        ".long ","",HEX_0X
    },
    {"gcc-cygwin",
        ".globl _%s\n"
        "\t.section .rodata\n"
        "\t.align 8\n" /* Either align 8 bytes or 2^8 (256) bytes. 8 bytes is needed. */
        "_%s:\n\n",

        ".long ","",HEX_0X
    },
    {"sun",
        "\t.section \".rodata\"\n"
        "\t.align   8\n"
        ".globl     %s\n"
        "%s:\n",

        ".word ","",HEX_0X
    },
    {"sun-x86",
        "Drodata.rodata:\n"
        "\t.type   Drodata.rodata,@object\n"
        "\t.size   Drodata.rodata,0\n"
        "\t.globl  %s\n"
        "\t.align  8\n"
        "%s:\n",

        ".4byte ","",HEX_0X
    },
    {"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
    },
    { "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 < (int32_t)(sizeof(assemblyHeader)/sizeof(assemblyHeader[0])); 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 < (int32_t)(sizeof(assemblyHeader)/sizeof(assemblyHeader[0])); 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) {
    uint32_t column = MAX_COLUMN;
    char entry[64];
    uint32_t buffer[1024];
    char *bufferStr = (char *)buffer;
    FileStream *in, *out;
    size_t i, length;

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

    if (outFilePath != NULL) {
        uprv_strcpy(outFilePath, bufferStr);
    }

#ifdef WINDOWS_WITH_GNUC
    /* Need to fix the file seperator 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]='_';
        }
    }

    sprintf(bufferStr, assemblyHeader[assemblyHeaderIndex].header,
        entry, entry, entry, entry,
        entry, entry, entry, entry);
    T_FileStream_writeLine(out, bufferStr);
    T_FileStream_writeLine(out, assemblyHeader[assemblyHeaderIndex].beginLine);

    for(;;) {
        length=T_FileStream_read(in, buffer, sizeof(buffer));
        if(length==0) {
            break;
        }
        if (length != sizeof(buffer)) {
            /* pad with extra 0's when at the end of the file */
            for(i=0; i < (length % sizeof(uint32_t)); ++i) {
                buffer[length+i] = 0;
            }
        }
        for(i=0; i<(length/sizeof(buffer[0])); i++) {
            column = write32(out, buffer[i], column);
        }
    }

    T_FileStream_writeLine(out, "\n");

    sprintf(bufferStr, assemblyHeader[assemblyHeaderIndex].footer,
        entry, entry, entry, entry,
        entry, entry, entry, entry);
    T_FileStream_writeLine(out, bufferStr);

    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) {
    uint32_t column = MAX_COLUMN;
    char buffer[4096], entry[64];
    FileStream *in, *out;
    size_t i, length;

    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_' */
      strcpy(entry, optName);
      strcat(entry, "_");
    } else {
      entry[0] = 0;
    }

    getOutFilename(filename, destdir, buffer, entry+uprv_strlen(entry), ".c", optFilename);
    if (outFilePath != NULL) {
        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]='_';
        }
    }

#ifdef 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]
    */
    sprintf(buffer,
        "#define U_DISABLE_RENAMING 1\n"
        "#include \"unicode/umachine.h\"\n"
        "U_CDECL_BEGIN\n"
        "const struct {\n"
        "    double bogus;\n"
        "    const char *bytes; \n"
        "} %s={ 0.0, \n",
        entry);
    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 */
    sprintf(buffer,
        "#define U_DISABLE_RENAMING 1\n"
        "#include \"unicode/umachine.h\"\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);
    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;
}

#ifdef 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, char *entryName, const char *newSuffix, const char *optFilename) {
    const char *basename=findBasename(inFilename), *suffix=uprv_strrchr(basename, '.');

    /* copy path */
    if(destdir!=NULL && *destdir!=0) {
        do {
            *outFilename++=*destdir++;
        } while(*destdir!=0);
        if(*(outFilename-1)!=U_FILE_SEP_CHAR) {
            *outFilename++=U_FILE_SEP_CHAR;
        }
        inFilename=basename;
    } else {
        while(inFilename<basename) {
            *outFilename++=*inFilename++;
        }
    }

    if(suffix==NULL) {
        /* the filename does not have a suffix */
        uprv_strcpy(entryName, inFilename);
        if(optFilename != NULL) {
          uprv_strcpy(outFilename, optFilename);
        } else {
          uprv_strcpy(outFilename, inFilename);
        }
        uprv_strcat(outFilename, newSuffix);
    } else {
        char *saveOutFilename = outFilename;
        /* copy basename */
        while(inFilename<suffix) {
            if(*inFilename=='-') {
                /* iSeries cannot have '-' in the .o objects. */
                *outFilename++=*entryName++='_';
                inFilename++;
            }
            else {
                *outFilename++=*entryName++=*inFilename++;
            }
        }

        /* replace '.' by '_' */
        *outFilename++=*entryName++='_';
        ++inFilename;

        /* copy suffix */
        while(*inFilename!=0) {
            *outFilename++=*entryName++=*inFilename++;
        }

        *entryName=0;

        if(optFilename != NULL) {
            uprv_strcpy(saveOutFilename, optFilename);
            uprv_strcat(saveOutFilename, newSuffix);
        } else {
            /* add ".c" */
            uprv_strcpy(outFilename, newSuffix);
        }
    }
}

#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 defined(U_WINDOWS)
        IMAGE_FILE_HEADER header;
#endif
    } buffer;

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

#ifdef U_ELF

#elif defined(U_WINDOWS)
    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 defined(U_WINDOWS)
/* _M_IA64 should be defined in windows.h */
#   if defined(_M_IA64)
        *pCPU=IMAGE_FILE_MACHINE_IA64;
#   elif defined(_M_AMD64)
        *pCPU=IMAGE_FILE_MACHINE_AMD64;
#   else
        *pCPU=IMAGE_FILE_MACHINE_I386;
#   endif
        *pBits= *pCPU==IMAGE_FILE_MACHINE_I386 ? 32 : 64;
        *pIsBigEndian=FALSE;
#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<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 defined(U_WINDOWS)
    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) {
    /* common variables */
    char buffer[4096], entry[40]={ 0 };
    FileStream *in, *out;
    const char *newSuffix;
    int32_t i, entryLength, length, size, entryOffset=0, entryLengthOffset=0;

    uint16_t cpu, bits;
    UBool makeBigEndian;

    /* 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
        },
        { /* .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
        },
        { /* 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
        },
        { /* .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
        },
        { /* 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 defined(U_WINDOWS)
    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);
    printf("genccode: --match-arch cpu=%hu bits=%hu big-endian=%hu\n", cpu, bits, makeBigEndian);
#ifdef U_WINDOWS
    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, entry+entryOffset, newSuffix, optFilename);
    if (outFilePath != NULL) {
        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 defined(U_WINDOWS)
    /* 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 */
    uprv_strcpy(objHeader.linkerOptions, "-export:");
    length=8;
    uprv_strcpy(objHeader.linkerOptions+length, entry);
    length+=entryLength;
    uprv_strcpy(objHeader.linkerOptions+length, ",data ");
    length+=6;

    /* 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);
    }

#ifdef U_WINDOWS
    /* 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