Re: Time functions in newlib

["J. Johnston" <jjohnstn at cygnus dot com>]

"Lewin A.R.W. Edwards" wrote:
> 
> Hi Cliff,
> 
> > > I'm working with a custom ARM7 platform, and I'm basically linking with
> > > newlib only to get access to a few math functions that are inserted
> > > * time-based functions, e.g. clock()? Is there a global tick count
> >variable
> > > I can just increment in an ISR?
> >
> >For clock(),you need a libgloss function:times(),
> >That is dependent on your hardware.
> 
> Libgloss isn't supported on arm-unknown-elf, or at least the newlib
> configure script tells me it isn't.
> 

Arm is one of those relics where the syscalls were originally put in the libc/sys directory.  You
will find the syscalls defined in newlib/libc/sys/arm/syscalls.c.  There is an _times routine
supplied which uses an SWI call.

> > > functions. How do I tell newlib where its heap begins and ends? (In my
> >
> >Specify the heap begin and end in the linker script,
> 
> Er, but what are the names of the symbols? :)
> 

The syscalls.c file also supplies an _sbrk routine which supports malloc.  It is looking for the
"end" symbol (end of bss) and increments forward from that symbol until it meets the stack pointer.

-- Jeff J.