#!/usr/bin/env bash
#set -x
input_file=$1
output_file=$2

# Preprocess cygtls.h and filter out only the member lines from
# class _cygtls to generate an input file for the cross compiler
# to generate the member offsets for tlsoffsets-$(target_cpu).h.
${CXXCOMPILE} -E -P "${input_file}" 2> /dev/null | \
gawk '
  BEGIN {
    # marker is used to split out the member lines from class _cygtls
    marker=0;
    # Prepare the input file for the subsequent compiler run.
    # Prepend value of __CYGTLS_PADSIZE__ so we can compute the offsets
    # up and down at the same time
    print "#include \"winsup.h\"";
    print "#include \"cygtls.h\"";
    print "extern \"C\" const uint32_t __CYGTLS__start_offset = __CYGTLS_PADSIZE__;";
  }
  /^class _cygtls$/ {
    # Ok, bump marker, next we are expecting a "public:" line
    marker=1;
  }
  /^public:/ {
    # We are only interested in the lines between the first (marker == 2)
    # and the second (marker == 3) "public:" line in class _cygtls.  These
    # are where the members are defined.
    if (marker > 0) ++marker;
    if (marker > 2) exit;
  }
  {
    if (marker == 2 && $1 != "public:") {
      # Filter out function names
      $0 = gensub (/\(\*(\w+)\)\s*\([^\)]*\)/, "\\1", "g");
      # Filter out leading asterisk
      $NF = gensub (/^\**(\w+)/, "\\1", "g", $NF);
      # Filter out trailing array expression
      $NF = gensub (/(\w+)\s*\[[^\]]*\]/, "\\1", "g", $NF);
      $NF = gensub (/(\w+);/, "\\1", "g", $NF);
      print "extern \"C\" const uint32_t __CYGTLS__" $NF " = offsetof (class _cygtls, " $NF ");";
    }
  }
' | \
# Now run the compiler to generate an assembler file.
${CXXCOMPILE} -x c++ -g0 -O0 -S - -o - | \
# The assembler file consists of lines like these:
#
#   __CYGTLS__foo
#       .long 42
#       .globl __CYGTLS__foo
#       .align 4
#
# From this info, generate the tlsoffsets file.
gawk '\
  BEGIN {
    varname=""
    start_offset = 0
  }
  /^__CYGTLS__/ {
    varname = gensub (/__CYGTLS__(\w+):/, "\\1", "g");
  }
  /\s*\.space\s*4/ {
    if (length (varname) > 0) {
      printf (".equ _cygtls.%s, %d\n", varname, -start_offset);
      printf (".equ _cygtls.%s_p, 0\n", varname);
      varname = "";
    }
  }
  /\s*\.long\s+/ {
    if (length (varname) > 0) {
      if (varname == "start_offset") {
      	start_offset = $2;
	printf (".equ _cygtls.%s, -%u\n", varname, start_offset);
      } else {
      	value = $2;
	printf (".equ _cygtls.%s, %d\n", varname, value - start_offset);
	printf (".equ _cygtls.%s_p, %d\n", varname, value);
      }
      varname = "";
    }
  }
' > "${output_file}"