Hi Richard,
Richard Erlacher schrieb:
> What is it that you fellows use to simulate 805x ASM code? I've found that
> the simulator bundled with SDCC for Windows doesn't operate on code that
> spans over 2 KB of memory, and I find I can't buy a "full" version of that
> simulator, as the company that owns/owned it no longer exists.
Can you be more explicit? - which simulator?
> I'm trying to produce some precisely timed code that uses large tables,
> don't want a compiler fiddling with my cycle counts, yet want, later, to be
> able to incorporate this code with other code written in 'C'.
Don't know whether you like it/whether the proposal below meets
your requirements (could f.e. be good enough for 1-wire timing).
Somewhat ugly but would this do?
-------8<-----------------------------------------------------------------
/* 8051 timer example. noninvasive. no cumulative errors. untested. untested.
*/
#include <8052.h>
extern void timer0_init ( void );
#define DELTA_T_SHORT 32;
#define DELTA_T_LONG 48;
/* Macro loops while (signed char)(x - TL0) is >= 0
So longest intervall is about 0x80 TL0 units.
Macro introduces a jitter of about y instructions
(z cycles), depending on memory area of (x). */
#define WAIT_EXPIRED_TL0(x) do{ while(!(0x80 & (char)((x)-TL0))) ; } while(0)
void main()
{
unsigned char next_event_tl0;
timer0_init();
/* next event to happen DELTA_T_SHORT (in TL0 ticks) from NOW */
next_event_tl0 = TL0 + DELTA_T_SHORT;
while ( 1 )
{
WAIT_EXPIRED_TL0( next_event_tl0 );
/* just to do something */
P3_1 = 1;
/* by adding to next_event_tl0 there is NO cumulative error.
Things look nice on an oscilloscope even if a (short)
IRQ interfered */
next_event_tl0 += DELTA_T_SHORT;
WAIT_EXPIRED_TL0( next_event_tl0 );
P3_1 = 0;
next_event_tl0 += DELTA_T_LONG;
/* note, we have NOT reset or otherwise modified
Timer0, or claimed usage of its overflow bit,
so actually we are pretty harmless while still
achieving "reasonable" accuracy. */
}
}
------->8-----------------------------------------------------------------
-------8<-----------------------------------------------------------------
361 _main:
370 ; timer.c:21: timer0_init();
0000 12s00r00 371 lcall _timer0_init
372 ; timer.c:24: next_event_tl0 = TL0 +
DELTA_T_SHORT;
0003 74 20 373 mov a,#0x20
0005 25 8A 374 add a,_TL0
0007 FA 375 mov r2,a
376 ; timer.c:28: WAIT_EXPIRED_TL0(
next_event_tl0 );
0008 377 00101$:
0008 EA 378 mov a,r2
0009 C3 379 clr c
000A 95 8A 380 subb a,_TL0
000C 30 E7 F9 381 jnb acc.7,00101$
382 ; timer.c:31: P3_1 = 1;
000F D2 B1 383 setb _P3_1
384 ; timer.c:36: next_event_tl0 +=
DELTA_T_SHORT;
0011 74 20 385 mov a,#0x20
0013 2A 386 add a,r2
0014 FA 387 mov r2,a
388 ; timer.c:39: WAIT_EXPIRED_TL0(
next_event_tl0 );
0015 389 00107$:
0015 EA 390 mov a,r2
0016 C3 391 clr c
0017 95 8A 392 subb a,_TL0
0019 30 E7 F9 393 jnb acc.7,00107$
394 ; timer.c:40: P3_1 = 0;
001C C2 B1 395 clr _P3_1
396 ; timer.c:41: next_event_tl0 +=
DELTA_T_LONG;
001E 74 30 397 mov a,#0x30
0020 2A 398 add a,r2
0021 FA 399 mov r2,a
0022 80 E4 400 sjmp 00101$
------->8-----------------------------------------------------------------
If you have to do cycle counting you are probably aware of
http://www.8052.com/users/disasm/
which can produce disassembled code along with the needed
instruction cycles (at least as long no prefetch/cache/spi
reads are involved).
Greetings,
Frieder
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