# Script to generate constants for Python pretty printers.

#

# Copyright (C) 2016-2018 Free Software Foundation, Inc.

# This file is part of the GNU C Library.

#

# The GNU C Library is free software; you can redistribute it and/or

# modify it under the terms of the GNU Lesser General Public

# License as published by the Free Software Foundation; either

# version 2.1 of the License, or (at your option) any later version.

#

# The GNU C Library is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# Lesser General Public License for more details.

#

# You should have received a copy of the GNU Lesser General Public

# License along with the GNU C Library; if not, see

# <http://www.gnu.org/licenses/>.

# This script is a smaller version of the clever gen-asm-const.awk hack used to

# generate ASM constants from .sym files.  We'll use this to generate constants

# for Python pretty printers.

#

# The input to this script are .pysym files that look like:

# #C_Preprocessor_Directive...

# NAME1

# NAME2 expression...

#

# A line giving just a name implies an expression consisting of just that name.

# Comments start with '--'.

#

# The output of this script is a 'dummy' function containing 'asm' declarations

# for each non-preprocessor line in the .pysym file.  The expression values

# will appear as input operands to the 'asm' declaration.  For example, if we

# have:

#

# /* header.h */

# #define MACRO 42

#

# struct S {

#     char c1;

#     char c2;

#     char c3;

# };

#

# enum E {

#     ZERO,

#     ONE

# };

#

# /* symbols.pysym */

# #include <stddef.h>

# #include "header.h"

# -- This is a comment

# MACRO

# C3_OFFSET offsetof(struct S, c3)

# E_ONE ONE

#

# the output will be:

#

# #include <stddef.h>

# #include "header.h"

# void dummy(void)

# {

#   asm ("@name@MACRO@value@%0@" : : "i" (MACRO));

#   asm ("@name@C3_OFFSET@value@%0@" : : "i" (offsetof(struct S, c3)));

#   asm ("@name@E_ONE@value@%0@" : : "i" (ONE));

# }

#

# We'll later feed this output to gcc -S.  Since '-S' tells gcc to compile but

# not assemble, gcc will output something like:

#

# dummy:

# 	...

# 	@name@MACRO@value@$42@

# 	@name@C3_OFFSET@value@$2@

# 	@name@E_ONE@value@$1@

#

# Finally, we can process that output to extract the constant values.

# Notice gcc may prepend a special character such as '$' to each value.

# found_symbol indicates whether we found a non-comment, non-preprocessor line.

BEGIN { found_symbol = 0 }

# C preprocessor directives go straight through.

/^#/ { print; next; }

# Skip comments.

/--/ { next; }

# Trim leading whitespace.

{ sub(/^[[:blank:]]*/, ""); }

# If we found a non-comment, non-preprocessor line, print the 'dummy' function

# header.

NF > 0 && !found_symbol {

    print "void dummy(void)\n{";

    found_symbol = 1;

}

# If the line contains just a name, duplicate it so we can use that name

# as the value of the expression.

NF == 1 { sub(/^.*$/, "& &";; }

# If a line contains a name and an expression...

NF > 1 {

    name = $1;

    # Remove any characters before the second field.

    sub(/^[^[:blank:]]+[[:blank:]]+/, "");

    # '$0' ends up being everything that appeared after the first field

    # separator.

    printf "  asm (\"@name@%s@value@%0@\" : : \"i\" (%s));\n", name, $0;

}

# Close the 'dummy' function.

END { if (found_symbol) print "}"; }