John,
What you are missing in your compiler invocation is "-W -Wall". This
will produce warnings when you use functions that don't have a prototype,
and can save you hours of trouble. It's my personal requirement that I get
a clean compile (no errors, no warnings) before I start actually debugging.
printf() is a funky creature because it is a variable argument function,
which means parameters are handled differently than other functions.
Whereas some functions can have arguments passed in registers, a variable
argument function will ALWAYS have it's arguments on the stack.
--John
-----Original Message-----
From: [email protected]
[mailto:[email protected]]on Behalf Of John Shanton
Sent: Thursday, August 29, 2002 14:37
To: [email protected]
Subject: [Mspgcc-users] Problem with uprintf() when compiled in multiple
files.
Problem with uprintf() when compiled in multiple files.
I have three source code files, p2a-reva.c, fpga_IO.c, and serial_IO.c.
The first one is where main() resides. The file fpga_IO.c has a call to
uprintf() with a transmit character function pointer to txChar().
When I compile it as a single file (#include the latter two files into the
first file), it generates good code in which the setup before a call to
uprintf() consists of two push opcodes. The first push points to the format
string and the second push points to the txChar function.
The problem I have is that when I compile the code with the following
command:
msp430-gcc -mmcu=msp430x149 -mIAR -o p2a-reva -O p2a-reva.c fpga_IO.c
serial_IO.c
I get code generated such that functions in the fpga_IO.c (second) file
has mov r14 and mov r15 instructions instead of push instructions before the
call to uprintf(). Functions in the first file still have the correct push
instructions prior to the call to uprintf().
The following are the generated assembler code fragments:
Call to function uprintf( txChar, "done\n\r"); from function in source
file fpga_IO.c
26d4: 3e 40 ae 26 mov #9902, r14 ; #0x26ae
26d8: 3f 40 46 27 mov #10054, r15 ; #0x2746
26dc: b0 12 24 34 call #13348 ; #0x3424
Call to function uprintf( txChar, "done\n\r"); from function in source
file p2a-reva.c
11a2: 30 12 61 11 push #4449 ; #0x1161
11a6: 30 12 46 27 push #10054 ; #0x2746
11aa: b0 12 24 34 call #13348 ; #0x3424
Note that address 0x2746 is the function txChar() that should be used by
uprintf(). Uprintf() is at address 0x3424. Both functions are calling the
exact same uprintf() routine but with a different set up before calling.
The code in the first function should use push instead of mov before calling
the uprint() function.
What am I doing wrong?
Thanks.
John L. Shanton III
Little Optics, Inc.
