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--- blog:ql_dev1 [2021/12/14 13:05] – [C68 Cross-Compiler (aka XTC68)] john
+++ blog:ql_dev1 [2021/12/16 11:03] (current) – john
@@ Line 23: / Line 23: @@
    * {{ :blog:sinclair:c68_linux64-2021_12_14.tgz |}} - Pre-compiled, with headers and runtime libraries. Unpacks to ///opt/toolchains/qdos//
    * {{ :blog:sinclair:c68.pdf |}} - C68 User Manual. For the original Sinclair QL hosted version, but most of the compiler and linker flags and options remain the same.
+   * {{ :blog:sinclair:c68_documentation_-_dave_walker.pdf |}} - A more in-depth manual about the use of C68, including a //basic// reference of available calls.
 === Sample C68 Makefile ===
@@ Line 110: / Line 111: @@
 	$(CC) $(CFLAGS) $(INCLUDES) -c other.c
 </code>
+=== Running C68 ===
+If you use a sample makefile such as the one above, you should get an output such as this:
+<code>
+$ make
+qcc -O  -c test.c
+qcc -O  -c other.c
+qld -v test.o other.o  -o game
+ld v1.22  QL 68000 SROFF Linker
+COMMENT: C68 crt_o v4.24f
+COMMENT: C68 libc_a v4.24f
+---------------------------
+SECTION      START   LENGTH
+---------------------------
+TEXT             0     3AD6
+DATA          3ad6      2FA
+UDATA         3dd0      4EE
+---------------------------
+Program length   =     42be
+Relocation table =      1ef
+--------------------
+Memory Usage     =       0%
+Buffer Usage     =       0%
+--------------------
+game: dataspace 870 (366)
+Link completed
+</code>
+This is mostly easy to understand - two passes of the compiler; one for each source file, then the linker takes the two object files, adds-in //crt.o// and any functions from the //standard library//. The output is a little more verbose than the usual compiler though - an important element being the //dataspace// that the resulting binary will take up in the QL memory.
+If you hexdump the binary, you will see some trailing data that mirrors that //dataspace// number:
+<code>
+$ hexdump -C game
+.
+.
+.
+fa0  04 04 04 04 04 04 04 04  04 0e 14 0c 04 04 0c 16  |................|
+fb0  14 26 08 04 04 04 04 48  04 06 60 01 24 38 00 00  |.&.....H..`.$8..|
+fc0  58 54 63 63 00 00 03 66                           |XTcc...f|
+fc8
+</code>
+This is referred to as the //xtcc field// and is used by the **qlzip** utility when unpacking on the QL native filesystem to restore the needed metadata about the application.
 ==== GCC Cross-Compiler ====
@@ Line 133: / Line 182: @@
      * https://github.com/NormanDunbar/qltools
      * Works with native QL floppy disks (DD 720K, HD 1440K or ED 3.2MB) or disk images to transfer files to/from those devices from Linux.
+==== Other Stuff ====
+I wrote a quick Python script to print out the value of an XTcc field in a binary produced by C68, GCC or similar. This is useful when copying an executable into a QL floppy or hard drive filesystem and you need to set the //dataspace parameter//:
+<code>
+#!/usr/bin/env python
+####################################
+#
+# Prints out the value of a Sinclar
+# QL binary XTcc field, as needed to
+# turn it into an executable file
+# on the QL itself, or when transferred
+# using qltool.
+#
+# John Snowdon, 2021
+#
+####################################
+import sys
+import os
+if len(sys.argv) < 2:
+	print("ERROR: No filename given")
+	sys.exit(-1)
+ql_filename = sys.argv[1]
+if (os.path.exists(ql_filename)):
+	f = open(ql_filename, "rb")
+	filedata = f.read()
+	offset = filedata.find(b'\x00XTcc')
+	if offset:
+		# First byte of "XTcc" is at 'offset', so jump by 4 bytes
+		f.seek(offset + 5)
+		dataspace = f.read(4)
+		# Print out the value of the dataspace field
+		print(int.from_bytes(dataspace, byteorder='big'))
+	f.close()
+else:
+	print("ERROR: Filename does not exist")
+	sys.exit(-1)
+</code>
+Just call the script with the name of your C68 executable. For example:
+<code>
+$ xtcc game.bin
+</code>
+... the value printed is the size of the dataspace needed. So you would then copy and mark your binary with qltools as follows:
+<code>
+$ xtcc game.bin
+$ qltools floppy.img -W game.bin
+$ qltools floppy.img -x game.bin 868
+</code>
+Or even easier, embed the xtcc call in backticks:
+<code>
+$ qltools floppy.img -W game.bin
+$ qltools floppy.img -x game.bin `xtcc game.bin`
+</code>