/******************************************************************************
  FILE        : datapage.c
  PURPOSE     : paged data access runtime routines
  MACHINE     : Freescale 68HC12 (Target)
  LANGUAGE    : ANSI-C
  HISTORY     : 21.7.96 first version created
******************************************************************************/

#include "hidef.h"

#include "non_bank.sgm"
#include "runtime.sgm"



#ifndef __HCS12X__ /* it's different for the HCS12X. See the text below at the #else // __HCS12X__ */

/*
   According to the -Cp option of the compiler the
   __DPAGE__, __PPAGE__ and __EPAGE__ macros are defined.
   If none of them is given as argument, then no page accesses should occur and
   this runtime routine should not be used !
   To be on the save side, the runtime routines are created anyway.
   If some of the -Cp options are given an adapted versions which only covers the
   needed cases is produced.
*/

/* if no compiler option -Cp is given, it is assumed that all possible are given : */

/* Compile with option -DHCS12 to activate this code */
#if defined(HCS12) || defined(_HCS12) || defined(__HCS12__) /* HCS12 family has PPAGE register only at 0x30 */
#define PPAGE_ADDR (0x30+REGISTER_BASE)
#ifndef __PPAGE__ /* may be set already by option -CPPPAGE */
#define __PPAGE__
#endif
/* Compile with option -DDG128 to activate this code */
#elif defined DG128 /* HC912DG128 derivative has PPAGE register only at 0xFF */
#define PPAGE_ADDR (0xFF+REGISTER_BASE)
#ifndef __PPAGE__ /* may be set already by option -CPPPAGE */
#define __PPAGE__
#endif
#elif defined(HC812A4)
/* all setting default to A4 already */
#endif


#if !defined(__EPAGE__) && !defined(__PPAGE__) && !defined(__DPAGE__)
/* as default use all page registers */
#define __DPAGE__
#define __EPAGE__
#define __PPAGE__
#endif

/* modify the following defines to your memory configuration */

#define EPAGE_LOW_BOUND   0x400u
#define EPAGE_HIGH_BOUND  0x7ffu

#define DPAGE_LOW_BOUND   0x7000u
#define DPAGE_HIGH_BOUND  0x7fffu

#define PPAGE_LOW_BOUND   (DPAGE_HIGH_BOUND+1)
#define PPAGE_HIGH_BOUND  0xBFFFu

#define REGISTER_BASE      0x0u
#ifndef DPAGE_ADDR
#define DPAGE_ADDR        (0x34u+REGISTER_BASE)
#endif
#ifndef EPAGE_ADDR
#define EPAGE_ADDR        (0x36u+REGISTER_BASE)
#endif
#ifndef PPAGE_ADDR
#define PPAGE_ADDR        (0x35u+REGISTER_BASE)
#endif

/*
  The following parts about the defines are assumed in the code of _GET_PAGE_REG :
  - the memory region controlled by DPAGE is above the area controlled by the EPAGE and
    below the area controlled by the PPAGE.
  - the lower bound of the PPAGE area is equal to be the higher bound of the DPAGE area + 1
*/
#if EPAGE_LOW_BOUND >= EPAGE_HIGH_BOUND || EPAGE_HIGH_BOUND >= DPAGE_LOW_BOUND || DPAGE_LOW_BOUND >= DPAGE_HIGH_BOUND || DPAGE_HIGH_BOUND >= PPAGE_LOW_BOUND || PPAGE_LOW_BOUND >= PPAGE_HIGH_BOUND
#error /* please adapt _GET_PAGE_REG for this non default page configuration */
#endif

#if DPAGE_HIGH_BOUND+1 != PPAGE_LOW_BOUND
#error /* please adapt _GET_PAGE_REG for this non default page configuration */
#endif


/* this module does either control if any access is in the bounds of the specified page or */
/* ,if only one page is specified, just use this page. */
/* This behavior is controlled by the define USE_SEVERAL_PAGES. */
/* If !USE_SEVERAL_PAGES does increase the performance significantly */
/* NOTE : When !USE_SEVERAL_PAGES, the page is also set for accesses outside of the area controlled */
/*        by this single page. But this is should not cause problems because the page is restored to the old value before any other access could occur */

#if !defined(__DPAGE__) && !defined(__EPAGE__) && !defined(__PPAGE__)
/* no page at all is specified */
/* only specifying the right pages will speed up these functions a lot */
#define USE_SEVERAL_PAGES 1
#elif defined(__DPAGE__) && defined(__EPAGE__) || defined(__DPAGE__) && defined(__PPAGE__) || defined(__EPAGE__) && defined(__PPAGE__)
/* more than one page register is used */
#define USE_SEVERAL_PAGES 1
#else

#define USE_SEVERAL_PAGES 0

#if defined(__DPAGE__) /* check which pages are used  */
#define PAGE_ADDR PPAGE_ADDR
#elif defined(__EPAGE__)
#define PAGE_ADDR EPAGE_ADDR
#elif defined(__PPAGE__)
#define PAGE_ADDR PPAGE_ADDR
#else /* we do not know which page, decide it at runtime */
#error /* must not happen */
#endif

#endif


#if USE_SEVERAL_PAGES /* only needed for several pages support */
/*--------------------------- _GET_PAGE_REG --------------------------------
  Runtime routine to detect the right register depending on the 16 bit offset part
  of an address.
  This function is only used by the functions below.

  Depending on the compiler options -Cp different versions of _GET_PAGE_REG are produced.

  Arguments :
  - Y : offset part of an address

  Result :
  if address Y is controlled by a page register :
  - X : address of page register if Y is controlled by an page register
  - Zero flag cleared
  - all other registers remain unchanged

  if address Y is not controlled by a page register :
  - Zero flag is set
  - all registers remain unchanged

  --------------------------- _GET_PAGE_REG ----------------------------------*/

#if defined(__DPAGE__)

#ifdef __cplusplus
extern "C"
#endif
#pragma NO_ENTRY
#pragma NO_EXIT
#pragma NO_FRAME

static void NEAR _GET_PAGE_REG(void) { /*lint -esym(528, _GET_PAGE_REG) used in asm code */
  __asm {
L_DPAGE:
        CPY     #DPAGE_LOW_BOUND  ;// test of lower bound of DPAGE
#if defined(__EPAGE__)
        BLO     L_EPAGE           ;// EPAGE accesses are possible
#else
        BLO     L_NOPAGE          ;// no paged memory below accesses
#endif
        CPY     #DPAGE_HIGH_BOUND ;// test of higher bound DPAGE/lower bound PPAGE
#if defined(__PPAGE__)
        BHI     L_PPAGE           ;// EPAGE accesses are possible
#else
        BHI     L_NOPAGE          ;// no paged memory above accesses
#endif
FOUND_DPAGE:
        LDX     #DPAGE_ADDR       ;// load page register address and clear zero flag
        RTS

#if defined(__PPAGE__)
L_PPAGE:
        CPY     #PPAGE_HIGH_BOUND ;// test of higher bound of PPAGE
        BHI     L_NOPAGE
FOUND_PPAGE:
        LDX     #PPAGE_ADDR       ;// load page register address and clear zero flag
        RTS
#endif

#if defined(__EPAGE__)
L_EPAGE:
        CPY     #EPAGE_LOW_BOUND  ;// test of lower bound of EPAGE
        BLO     L_NOPAGE
        CPY     #EPAGE_HIGH_BOUND ;// test of higher bound of EPAGE
        BHI     L_NOPAGE

FOUND_EPAGE:
        LDX     #EPAGE_ADDR       ;// load page register address and clear zero flag
        RTS
#endif

L_NOPAGE:
        ORCC    #0x04             ;// sets zero flag
        RTS
  }
}

#else /* !defined(__DPAGE__) */

#if defined( __PPAGE__ )

#ifdef __cplusplus
extern "C"
#endif
#pragma NO_ENTRY
#pragma NO_EXIT
#pragma NO_FRAME

static void NEAR _GET_PAGE_REG(void) {	/*lint -esym(528, _GET_PAGE_REG) used in asm code */
  __asm {
L_PPAGE:
        CPY     #PPAGE_LOW_BOUND  ;// test of lower bound of PPAGE
#if defined( __EPAGE__ )
        BLO     L_EPAGE
#else
        BLO     L_NOPAGE          ;// no paged memory below
#endif
        CPY     #PPAGE_HIGH_BOUND ;// test of higher bound PPAGE
        BHI     L_NOPAGE
FOUND_PPAGE:
        LDX     #PPAGE_ADDR       ;// load page register address and clear zero flag
        RTS
#if defined( __EPAGE__ )
L_EPAGE:
        CPY     #EPAGE_LOW_BOUND  ;// test of lower bound of EPAGE
        BLO     L_NOPAGE
        CPY     #EPAGE_HIGH_BOUND ;// test of higher bound of EPAGE
        BHI     L_NOPAGE
FOUND_EPAGE:
        LDX     #EPAGE_ADDR       ;// load page register address and clear zero flag
        RTS
#endif

L_NOPAGE:                         ;// not in any allowed page area
                                  ;// its a far access to a non paged variable
        ORCC #0x04                ;// sets zero flag
        RTS
  }
}

#else /* !defined(__DPAGE__ ) && !defined( __PPAGE__) */
#if defined(__EPAGE__)

#ifdef __cplusplus
extern "C"
#endif
#pragma NO_ENTRY
#pragma NO_EXIT
#pragma NO_FRAME

static void NEAR _GET_PAGE_REG(void) { /*lint -esym(528, _GET_PAGE_REG) used in asm code */
  __asm {
L_EPAGE:
        CPY     #EPAGE_LOW_BOUND  ;// test of lower bound of EPAGE
        BLO     L_NOPAGE
        CPY     #EPAGE_HIGH_BOUND ;// test of higher bound of EPAGE
        BHI     L_NOPAGE
FOUND_EPAGE:
        LDX     #EPAGE_ADDR       ;// load page register address and clear zero flag
        RTS

L_NOPAGE:                         ;// not in any allowed page area
                                  ;// its a far access to a non paged variable
        ORCC    #0x04             ;// sets zero flag
        RTS
  }
}

#endif /*  defined(__EPAGE__) */
#endif /*  defined(__PPAGE__) */
#endif /*  defined(__DPAGE__) */

#endif /* USE_SEVERAL_PAGES */

/*--------------------------- _SET_PAGE --------------------------------
  Runtime routine to set the right page register. This routine is used if the compiler
  does not know the right page register, i.e. if the option -Cp is used for more than
  one page register or if the runtime option is used for one of the -Cp options.

  Arguments :
  - offset part of an address in the Y register
  - page part of an address in the B register

  Result :
  - page part written into the correct page register.
  - the old page register content is destroyed
  - all processor registers remains unchanged
  --------------------------- _SET_PAGE ----------------------------------*/

#ifdef __cplusplus
extern "C"
#endif
#pragma NO_ENTRY
#pragma NO_EXIT
#pragma NO_FRAME

void NEAR _SET_PAGE(void) {
#if USE_SEVERAL_PAGES
  __asm {
        PSHX                      ;// save X register
        __PIC_JSR(_GET_PAGE_REG)
        BEQ     L_NOPAGE
        STAB    0,X               ;// set page register
L_NOPAGE:
        PULX                      ;// restore X register
        RTS
  }
#else /* USE_SEVERAL_PAGES */
  __asm {
        STAB    PAGE_ADDR         ;// set page register
        RTS
  }
#endif /* USE_SEVERAL_PAGES */
}

/*--------------------------- _LOAD_FAR_8 --------------------------------
  This runtime routine is used to access paged memory via a runtime function.
  It may also be used if the compiler option -Cp is not used with the runtime argument.

  Arguments :
  - offset part of an address in the Y register
  - page part of an address in the B register

  Result :
  - value to be read in the B register
  - all other registers remains unchanged
  - all page register still contain the same value
  --------------------------- _LOAD_FAR_8 ----------------------------------*/

#ifdef __cplusplus
extern "C"
#endif
#pragma NO_ENTRY
#pragma NO_EXIT
#pragma NO_FRAME

void NEAR _LOAD_FAR_8(void) {
#if USE_SEVERAL_PAGES
  __asm {
        PSHX                      ;// save X register
        __PIC_JSR(_GET_PAGE_REG)
        BEQ     L_NOPAGE
        PSHA                      ;// save A register
        LDAA    0,X               ;// save page register
        STAB    0,X               ;// set page register
        LDAB    0,Y               ;// actual load, overwrites page
        STAA    0,X               ;// restore page register
        PULA                      ;// restore A register
        PULX                      ;// restore X register
        RTS
L_NOPAGE:
        LDAB    0,Y               ;// actual load, overwrites page
        PULX                      ;// restore X register
        RTS
  }
#else /* USE_SEVERAL_PAGES */
  __asm {
        PSHA                      ;// save A register
        LDAA    PAGE_ADDR         ;// save page register
        STAB    PAGE_ADDR         ;// set page register
        LDAB    0,Y               ;// actual load, overwrites page
        STAA    PAGE_ADDR         ;// restore page register
        PULA                      ;// restore A register
        RTS
  }
#endif /* USE_SEVERAL_PAGES */
}