/* Automates setup of V25 on-chip baud-rate generator. Used like this:
	#define		BAUDSET_XTAL	16e+6
	#define		BAUDSET_DESIRED	9600ul
	#include	<baudset.h>	// or #include "baudset.h"
		...
		pokeb(PORT_SEG, SCC0, BAUDSET_SCC);
		pokeb(PORT_SEG, BRG0, BAUDSET_BRG); */

#if !defined(__BAUDSET_H)
#define __BAUDSET_H

#pragma warn -dup /* suppress warnings about re-defined macros (Borland) */

/* compute the value of the divisor (BRG register) if prescaled clock is
BAUDSET_XTAL / 4	(SCC register =0) */
#define BAUDSET_SCALE   4
#define BAUDSET_BRG     (int)(BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_DESIRED + 0.5)
#if     BAUDSET_BRG<2                                   /* baud rate too high */
#error  Desired baud can't be achieved with this crystal
#elif   BAUDSET_BRG<256                                 /* baud rate OK */
#define BAUDSET_SCC     0
#else
/* if divisor is too large, adjust prescale up and try again... */
#define BAUDSET_SCALE   8
#define BAUDSET_BRG     (int)(BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_DESIRED + 0.5)
#if     BAUDSET_BRG<2                                   /* baud rate too high */
#error  Desired baud can't be achieved with this crystal
#elif   BAUDSET_BRG<256                                 /* baud rate OK */
#define BAUDSET_SCC     1
#else
/* ...and again... */
#define BAUDSET_SCALE   16
#define BAUDSET_BRG     (int)(BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_DESIRED + 0.5)
#if     BAUDSET_BRG<2                                   /* baud rate too high */
#error  Desired baud can't be achieved with this crystal
#elif   BAUDSET_BRG<256                                 /* baud rate OK */
#define BAUDSET_SCC     2
#else
/* ...and again... */
#define BAUDSET_SCALE   32
#define BAUDSET_BRG     (int)(BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_DESIRED + 0.5)
#if     BAUDSET_BRG<2                                   /* baud rate too high */
#error  Desired baud can't be achieved with this crystal
#elif   BAUDSET_BRG<256                                 /* baud rate OK */
#define BAUDSET_SCC     3
#else
/* (you get the idea) */
#define BAUDSET_SCALE   64
#define BAUDSET_BRG     (int)(BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_DESIRED + 0.5)
#if     BAUDSET_BRG<2                                   /* baud rate too high */
#error  Desired baud can't be achieved with this crystal
#elif   BAUDSET_BRG<256                                 /* baud rate OK */
#define BAUDSET_SCC     4
#else

#define BAUDSET_SCALE   128
#define BAUDSET_BRG     (int)(BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_DESIRED + 0.5)
#if     BAUDSET_BRG<2                                   /* baud rate too high */
#error  Desired baud can't be achieved with this crystal
#elif   BAUDSET_BRG<256                                 /* baud rate OK */
#define BAUDSET_SCC     5
#else

#define BAUDSET_SCALE   256
#define BAUDSET_BRG     (int)(BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_DESIRED + 0.5)
#if     BAUDSET_BRG<2                                   /* baud rate too high */
#error  Desired baud can't be achieved with this crystal
#elif   BAUDSET_BRG<256                                 /* baud rate OK */
#define BAUDSET_SCC     6
#else

#define BAUDSET_SCALE   512
#define BAUDSET_BRG     (int)(BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_DESIRED + 0.5)
#if     BAUDSET_BRG<2                                   /* baud rate too high */
#error  Desired baud can't be achieved with this crystal
#elif   BAUDSET_BRG<256                                 /* baud rate OK */
#define BAUDSET_SCC     7
#else

#define BAUDSET_SCALE   1024
#define BAUDSET_BRG     (int)(BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_DESIRED + 0.5)
#if     BAUDSET_BRG<2                                   /* baud rate too high */
#error  Desired baud can't be achieved with this crystal
#elif   BAUDSET_BRG<256                                 /* baud rate OK */
#define BAUDSET_SCC     8
#else
#error  Desired baud can't be achieved with this crystal
#endif
#endif
#endif
#endif
#endif
#endif
#endif
#endif
#endif
/* one final check to see if actual baud rate is close enough to desired */
#define BAUDSET_ACTUAL  (BAUDSET_XTAL / BAUDSET_SCALE / BAUDSET_BRG)
#define BAUDSET_ERR     (BAUDSET_ACTUAL - BAUDSET_DESIRED) / BAUDSET_DESIRED

#if     (BAUDSET_ERR>0.05)||(BAUDSET_ERR<-0.05)
#error  Actual baud rate differs from desired > 5%
#endif

#endif  /* __BAUDSET_H */