Ticket #105: API_FPU_CW_Wrappers.awk

# This AWK script will take os2emx.h and create wrappers that restore
# the FPU control word to its normal state expected by C/C++ programs

BEGIN {
    if (ARGC != 2) {
        print "Usage: API_FPU_CW_Wrappers.awk <os2emx.h>";
        exit 1;
    }
    in_func_decl = 0;
    func_decl = ""
    num_funcs = 0
}

/^[a-zA-Z]+[ \t]+APIENTRY[ \t]+(Win|Gpi).*[ \t]+\(/ { in_func_decl = 1 }

in_func_decl { func_decl = func_decl $0 }

/;/ && in_func_decl {
    in_func_decl = 0
    funcs[num_funcs] = substr(func_decl, 1, length(func_decl)-1)
    func_decl = ""
    num_funcs++
}

END {
    print "/* Generated by API_FPU_CW_Wrappers.awk from os2emx.h      */"
    print "/* See http://svn.netlabs.org/qt4/ticket/105 for more info */"
    print ""
    print "/*"
    print " * Some OS/2 PM API calls modify the FPU Control Word,"
    print " * but forget to restore it."
    print " *"
    print " * This can result in unexpected XCPT_FLOAT_INVALID_OPCODE or"
    print " * XCPT_FLOAT_INVALID_OPERATION exceptions. To avoid this, we create"
    print " * wrappers for each API call that restore the FPU Control Word"
    print " * after the API call back to the value expected by C/C++ programs."
    print " */"
    print ""
    print "#ifndef API_FPU_CW_WRAPPERS_H"
    print "#define API_FPU_CW_WRAPPERS_H"
    print ""
    print "inline void __FPU_CW_Restore()"
    print "{"
    print "    asm(\"pushl %%eax\\n\\t\"       /* Dummy for storing control word */"
    print "        \"fstcw 0(%%esp)\\n\\t\"    /* Store control word into memory */"
    print "        \"orw $5, 0(%%esp)\\n\\t\"  /* Set EM_INVALID (0x1) | EM_ZERODIVIDE (0x4) */"
    print "        \"fldcw 0(%%esp)\\n\\t\"    /* Load control word back */"
    print "        \"popl %%eax\\n\\t\""
    print "        ::: \"eax\");"
    print "}"
    print ""

    for (i = 0; i < num_funcs; i++) {
        fnc = funcs[i]
        rv  = gensub("^(.*)[ \t]+APIENTRY.*", "\\1", "", fnc)
        fn = gensub(".*[ \t]+((Win|Gpi).*)[ \t]+\\(.*", "\\1", "", fnc)
        print "inline " gensub(fn, "__FPU_CW_" fn, "", fnc) "\n{"
        fn_args = gensub(".*\\((.*)\\).*", "\\1", "", fnc)
        fn_args = gensub("([_a-zA-Z][_a-zA-Z0-9]*[ \t]+)+\\*?([_a-zA-Z][_a-zA-Z0-9]*)(,[ \t]+|$)", "\\2\\3", "g", fn_args)
        if (toupper(fn_args) == "VOID")
            fn_args = ""
        print "    " rv " ret = " fn " (" fn_args ");"
        print "    __FPU_CW_Restore();"
        print "    return ret;\n}"
        print "#define " fn " __FPU_CW_" fn "\n"
    }

    print "#endif // API_FPU_CW_WRAPPERS_H"
}