compile-file: need endian mark in .tlo files.

VM machine code is endian-specific: it consists of 32 bit
instruction words which are 32 bit in the local byte order.

Thus code assembled on a little-endian machine won't run
on a big endian-machine, or vice versa: unless we identify
the situation and byte-swap the code when we load it.

* buf.c (buf_swap32): New function.

* buf.h (buf_swap32): Declared.

* parser.c (read_file_common): Decode the third element from
the version: a Boolean indicating big endian, if true.
If the object file's endian is opposite from our endian, then
byte swap the code.

* itypes.c (itypes_init): Oops, calculation of
itypes_little_endian was broken due to classic C =/== typo.
Luckily, nothing has used this flag so far; it's been waiting
for this first use. I caught this due to testing on a PPC64
box.

* share/txr/stdlib/compiler.tl (%big-endian%, %tlo-ver%): New
variables.
(usr:compile-file): The file version comes from %tlo-ver% now,
which includes the big-endian flag.

1 files changed, 14 insertions, 0 deletions

diff --git a/buf.c b/buf.c
index efd2e4a6..40e81607 100644
--- a/buf.c
+++ b/buf.c
@@ -914,6 +914,20 @@ val get_buf_from_stream(val stream)
   return s->buf;
 }
 
+void buf_swap32(val buf)
+{
+  val self = lit("buf-swap32");
+  struct buf *b = buf_handle(buf, self);
+  mem_t *data = b->data, *end = data + c_num(b->len);
+
+  for (; data + 3 < end; data += 4) {
+    u32_t sw32 = *coerce(u32_t *, data);
+    sw32 = ((sw32 & 0xFF00FF00U) >>  8) | ((sw32 & 0x00FF00FFU) <<  8);
+    sw32 = ((sw32 & 0xFFFF0000U) >> 16) | ((sw32 & 0x0000FFFFU) << 16);
+    *coerce(u32_t *, data) = sw32;
+  }
+}
+
 void buf_init(void)
 {
   reg_fun(intern(lit("make-buf"), user_package), func_n3o(make_buf, 1));