gdb code review, pointer madness

NZG
2006-01-23T20:39:42Z

I'm trying to get gdb 6.1's machine interface to work correctly with the m68k
arch, and I'm having some weird results.

I've noticed that if I do a (frame -1) command on gdb after connecting to
remote gdb server, but before breaking in the main program, gdb goes crazy
and starts requesting random memory locations from gdbserver until something
crashes.

Sooo... I'm using regular gdb to debug the m68k-elf-gdb connection, and I'm
seeing a problem "extract_unsigned_integer" (pasted below).

Specifically this loop doesn't seem to be executing correctly

for (p = startaddr; p < endaddr; ++p)
retval = (retval << 8) | *p;

In the function call I'm watching,
endaddr = startaddr+4,
yet, when I step through the function the loop executes 8 times and overshoots
the array.

I don't see anything wrong with the code.
Can anyone else see anything weird in the pointer math below?

thx,
NZG

ULONGEST
extract_unsigned_integer (const void *addr, int len)
{
ULONGEST retval;
const unsigned char *p;
const unsigned char *startaddr = addr;
const unsigned char *endaddr = startaddr + len;

if (len > (int) sizeof (ULONGEST))
error ("\
That operation is not available on integers of more than %d bytes.",
(int) sizeof (ULONGEST));

/* Start at the most significant end of the integer, and work towards
the least significant. */
retval = 0;
if (TARGET_BYTE_ORDER == BFD_ENDIAN_BIG)
{
for (p = startaddr; p < endaddr; ++p)
retval = (retval << 8) | *p;
}
else
{
for (p = endaddr - 1; p >= startaddr; --p)
retval = (retval << 8) | *p;
}
return retval;
}