scripts/get-structure-packing-info

#! /bin/sh

die () {
  echo "$1" 1>&2 
  exit 1
}

die_unless_set () {
  eval "isset=\$$1"
  test -z "$isset" && die "$1 not set"
}

# test_is_equal DEFINE_TYPE SIZEOF_TYPE EVAL_IF_TRUE
test_is_equal () {
  # Write out C file
  cat > test-compile-for-structure-packing-0.c <<EOF
#include <inttypes.h>
$1;
int main ()
{
  /* Program does not compile iff alignof(int32_t) is 2 */
  switch (0) { case $2: case sizeof(TYPE): ; }
}
EOF

  # If it DOESN'T compile, then the values are equal.
  $CC -o /dev/null test-compile-for-structure-packing-0.c > /dev/null 2>&1 || { eval "$3" ; }
  rm -f test-compile-for-structure-packing-0.c 
}
test_is_not_equal () {
  # Write out C file
  cat > test-compile-for-structure-packing-0.c <<EOF
#include <inttypes.h>
$1;
int main ()
{
  /* Program does not compile iff alignof(int32_t) is 2 */
  switch (0) { case $2: case sizeof(TYPE): ; }
}
EOF

  # If it DOESN'T compile, then the values are equal.
  $CC -o /dev/null test-compile-for-structure-packing-0.c > /dev/null 2>&1 && { eval "$3" ; }
  rm -f test-compile-for-structure-packing-0.c 
}


test_is_equal "typedef int TYPE" 2 "SIZEOF_INT=2"
test_is_equal "typedef int TYPE" 4 "SIZEOF_INT=4"
test_is_equal "typedef int TYPE" 8 "SIZEOF_INT=8"
die_unless_set SIZEOF_INT
test_is_equal "typedef void* TYPE" 2 "SIZEOF_POINTER=2"
test_is_equal "typedef void* TYPE" 4 "SIZEOF_POINTER=4"
test_is_equal "typedef void* TYPE" 8 "SIZEOF_POINTER=8"
die_unless_set SIZEOF_POINTER

test_is_not_equal "typedef float TYPE" 4 'die "expecting float to be 4 bytes"'
test_is_not_equal "typedef double TYPE" 8 'die "expecting double to be 4 bytes"'
test_is_equal "typedef struct { char c; int32_t i; }" 5 "ALIGNOF_INT32=1"
test_is_equal "typedef struct { char c; int32_t i; }" 6 "ALIGNOF_INT32=2"
test_is_equal "typedef struct { char c; int32_t i; }" 8 "ALIGNOF_INT32=4"
die_unless_set ALIGNOF_INT32
test_is_equal "typedef struct { char c; int64_t i; }" 9 "ALIGNOF_INT64=1"
test_is_equal "typedef struct { char c; int64_t i; }" 10 "ALIGNOF_INT64=2"
test_is_equal "typedef struct { char c; int64_t i; }" 12 "ALIGNOF_INT64=4"
test_is_equal "typedef struct { char c; int64_t i; }" 16 "ALIGNOF_INT64=8"
die_unless_set ALIGNOF_INT64
test_is_equal "typedef struct { char c; float i; }" 5 "ALIGNOF_FLOAT=1"
test_is_equal "typedef struct { char c; float i; }" 6 "ALIGNOF_FLOAT=2"
test_is_equal "typedef struct { char c; float i; }" 8 "ALIGNOF_FLOAT=4"
die_unless_set ALIGNOF_FLOAT
test_is_equal "typedef struct { char c; double i; }" 9 "ALIGNOF_DOUBLE=1"
test_is_equal "typedef struct { char c; double i; }" 10 "ALIGNOF_DOUBLE=2"
test_is_equal "typedef struct { char c; double i; }" 12 "ALIGNOF_DOUBLE=4"
test_is_equal "typedef struct { char c; double i; }" 16 "ALIGNOF_DOUBLE=8"
die_unless_set ALIGNOF_DOUBLE
case "$SIZEOF_POINTER" in
  2)
    test_is_equal "typedef struct { char c; void *i; }" 3 "ALIGNOF_POINTER=1"
    test_is_equal "typedef struct { char c; void *i; }" 4 "ALIGNOF_POINTER=2"
    ;;
  4)
    test_is_equal "typedef struct { char c; void *i; }" 5 "ALIGNOF_POINTER=1"
    test_is_equal "typedef struct { char c; void *i; }" 6 "ALIGNOF_POINTER=2"
    test_is_equal "typedef struct { char c; void *i; }" 8 "ALIGNOF_POINTER=4"
    ;;
  8)
    test_is_equal "typedef struct { char c; void *i; }" 9 "ALIGNOF_POINTER=1"
    test_is_equal "typedef struct { char c; void *i; }" 10 "ALIGNOF_POINTER=2"
    test_is_equal "typedef struct { char c; void *i; }" 12 "ALIGNOF_POINTER=4"
    test_is_equal "typedef struct { char c; void *i; }" 16 "ALIGNOF_POINTER=8"
    ;;
  *)
    die "bad SIZEOF_POINTER=$SIZEOF_POINTER"
esac
die_unless_set ALIGNOF_POINTER

case "$SIZEOF_INT" in
  2) ALIGNOF_INT=$ALIGNOF_INT16 ;;
  4) ALIGNOF_INT=$ALIGNOF_INT32 ;;
  8) ALIGNOF_INT=$ALIGNOF_INT64 ;;
  *) die "bad SIZEOF_INT=$SIZEOF_INT" ;;
esac

for a in SIZEOF_INT SIZEOF_POINTER \
         ALIGNOF_INT16 ALIGNOF_INT32 ALIGNOF_INT64 ALIGNOF_INT ALIGNOF_POINTER
do
  eval "v=\$$a"
  echo "#define $a $v"
done