Hi all,
I'm trying to understand how to use the μCsim simulator interface - the
interface between the program running within the simulator, and the
simulator itself. My aim is to have the program that's running in the
sim measure the execution time (i.e. no. of cycles) of some of it's own
code.
As far as I understand, you configure it by specifying a certain memory
location (not one which is used by the chip being simulated!) which
provides a single-byte 'register' of sorts through which your running
program can communicate with the simulator. I have that working, by
specifying command-line args of "-I if=rom[0x5800]" (I chose an address
just after the peripheral registers, in what is otherwise 'reserved'
address space). Then if I attempt, from within my running program, to
use the 'detect' command by writing the value 0x5F to that address, and
then read back, I successfully get the '!' response character. Similarly
I can read the interface version successfully (returns 0x01).
One thing I do not understand how to do, and the documentation does not
reveal, is how to read the simulator's configuration information. When
you (in the simulator console) issue the command "info hw simif", in
addition to the simif command summary, it shows:
Configuration memory of simif
0x00 00000001 . Turn simif on/off (bool, RW)
0x01 00000000 . WR: sets running state, RD: check if simulation is running
0x02 00000000 . WR: start simulation, RD: true if running
0x03 00000001 . WR: stop simulation, RD: true if stopped
0x04 00000000 . Quit simulator (any, WO)
0x05 0000006e n Reason of last stop (int, RO)
0x06 007a1200 . Xtal frequency in Hz (int, RW)
0x07 000a7db0 . Nuof ticks simulated so far (int, RO)
0x08 00000000 . Ticks spent in ISR (int, RO)
0x09 00000000 . Ticks spent in idle state (int, RO)
0x0a 00000055 U Real time since reset in msec (int, RO)
0x0b 00151ae2 . Nuof simulated virtual clocks (int, RO)
0x0c 000098e2 . PC register (int, RW)
0x0d 00000000 . Print char on stdout (int, WO)
0x0e 00000000 . Write char to simif output (int, WO)
0x0f 00000000 . Not used
How is one meant to read/write this data? I thought perhaps you write
the first byte to the simif memory location, then read 4 bytes back with
the value? But when I tried this to get, for example, the PC, I don't
read anything that looks like the correct data. I tried it two ways:
#define UCSIM_IF (*(volatile uint8_t *)(0x5800))
/* doesn't work, pc = 0xF3000000 */
UCSIM_IF = 0x0C;
uint32_t pc = (*(volatile uint32_t *)(&UCSIM_IF));
/* also doesn't work, pc = 0xF3F3F3F3 */
union {
uint32_t val;
uint8_t raw[4];
} pc;
UCSIM_IF = 0x0C;
pc.raw[0] = UCSIM_IF;
pc.raw[1] = UCSIM_IF;
pc.raw[2] = UCSIM_IF;
pc.raw[3] = UCSIM_IF;
Can anyone tell me how I am supposed to read the simif configuration values?
Regards,
Basil Hussain
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