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/******************************************************************************
  FILE        : start08.c 
  PURPOSE     : 68HC08 standard startup code
  LANGUAGE    : ANSI-C / INLINE ASSEMBLER
  ----------------------------------------------------------------------------
  HISTORY 
    22 oct 93         Created.
    04/17/97          Also C++ constructors called in Init().
 ******************************************************************************/

/**********************************************************************/
/* NOTE:                                                              */
/* This version of the startup code does assumes that main            */
/* does never return (saving the 2 byte return address of _Startup on */
/* the stack).                                                        */
/**********************************************************************/

#define __NO_FLAGS_OFFSET   /* we do not need the flags field in the startup data descriptor */
#define __NO_MAIN_OFFSET    /* we do not need the main field in the startup data descriptor */

#include <start08.h>

#ifdef __cplusplus
#define __EXTERN_C  extern "C"
#else
#define __EXTERN_C
#endif


/**********************************************************************/
/* __ONLY_INIT_SP define:                                             */
/* This define selects an shorter version of the startup code         */
/* which only loads the stack pointer and directly afterwards calls   */
/* main. This version does however NOT initialized global variables   */
/* (So this version is not ANSI compliant!)                           */
/**********************************************************************/

#ifndef __ONLY_INIT_SP   

#pragma DATA_SEG FAR _STARTUP
struct _tagStartup _startupData;    /* read-only:
                                     _startupData is allocated in ROM and
                                     initialized by the linker */

#pragma MESSAGE DISABLE C20001 /* Warning C20001: Different value of stackpointer depending on control-flow */
/* the function _COPY_L releases some bytes from the stack internally */

#ifdef __OPTIMIZE_FOR_SIZE__
#pragma NO_ENTRY
#pragma NO_EXIT
#pragma NO_FRAME
/*lint -esym(528, loadByte) inhibit warning about not referenced loadByte function */
static void near loadByte(void) {
  asm {
             PSHH
             PSHX
#ifdef __HCS08__
             LDHX    5,SP
             LDA     0,X
             AIX     #1
             STHX    5,SP
#else
             LDA     5,SP
             PSHA
             LDX     7,SP
             PULH
             LDA     0,X
             AIX     #1
             STX     6,SP
             PSHH
             PULX
             STX     5,SP
#endif
             PULX
             PULH
             RTS
  }
}
#endif /* __OPTIMIZE_FOR_SIZE__ */


/*lint -esym(752,_COPY_L)  inhibit message on dunction declared, but not used (it is used in HLI) */
__EXTERN_C extern void _COPY_L(void);
/* DESC:    copy very large structures (>= 256 bytes) in 16 bit address space (stack incl.)
   IN:      TOS count, TOS(2) @dest, H:X @src
   OUT:
   WRITTEN: X,H */
#ifdef __ELF_OBJECT_FILE_FORMAT__
        #define toCopyDownBegOffs 0
#else
        #define toCopyDownBegOffs 2 /* for the hiware format, the toCopyDownBeg field is a long. Because the HC08 is big endian, we have to use an offset of 2 */ 
#endif
static void Init(void) {
/* purpose:     1) zero out RAM-areas where data is allocated
                2) init run-time data
                3) copy initialization data from ROM to RAM
 */
  /*lint -esym(529,p,i)  inhibit warning about symbols not used: it is used in HLI below */
  int i;
  int *far p;

  asm {
ZeroOut:     ;
             LDA    _startupData.nofZeroOuts:1 ; nofZeroOuts
             INCA
             STA    i:1                        ; i is counter for number of zero outs
             LDA    _startupData.nofZeroOuts:0 ; nofZeroOuts
             INCA
             STA    i:0
             LDHX   _startupData.pZeroOut      ; *pZeroOut
             BRA    Zero_5
Zero_3:    ;
            ; CLR    i:1 is already 0
Zero_4:    ;
             ; { HX == _pZeroOut }
             PSHX
             PSHH
             ; { nof bytes in (int)2,X }
             ; { address in (int)0,X   }
             LDA    0,X
             PSHA
             LDA    2,X
             INCA
             STA    p                  ; p:0 is used for high byte of byte counter
             LDA    3,X
             LDX    1,X
             PULH
             INCA
             BRA    Zero_0
Zero_1:    ;
           ;  CLRA   A is already 0, so we do not have to clear it
Zero_2:    ;
             CLR    0,X
             AIX    #1
Zero_0:    ;
             DBNZA  Zero_2
Zero_6:
             DBNZ   p, Zero_1
             PULH
             PULX                           ; restore *pZeroOut
             AIX    #4                      ; advance *pZeroOut
Zero_5:    ;
             DBNZ   i:1, Zero_4
             DBNZ   i:0, Zero_3
             ;
CopyDown:    ;

  }

  /* copy down */
  /* _startupData.toCopyDownBeg  --->  {nof(16) dstAddr(16) {bytes(8)}^nof} Zero(16) */
#if defined(__OPTIMIZE_FOR_SIZE__)
  asm {
#ifdef __HCS08__
             LDHX   _startupData.toCopyDownBeg:toCopyDownBegOffs
             PSHX  
             PSHH  
#else
             LDA    _startupData.toCopyDownBeg:(1+toCopyDownBegOffs)
             PSHA  
             LDA    _startupData.toCopyDownBeg:(0+toCopyDownBegOffs)
             PSHA  
#endif
Loop0:             
             JSR    loadByte  ; load high byte counter
             TAX              ; save for compare
             INCA  
             STA    i
             JSR    loadByte  ; load low byte counter
             INCA  
             STA    i:1
             DECA
             BNE    notfinished
             CBEQX  #0, finished
notfinished:

             JSR    loadByte  ; load high byte ptr
             PSHA  
             PULH  
             JSR    loadByte  ; load low byte ptr
             TAX              ; HX is now destination pointer
             BRA    Loop1
Loop3:             
Loop2:             
             JSR    loadByte  ; load data byte
             STA    0,X
             AIX    #1
Loop1:
             DBNZ   i:1, Loop2
             DBNZ   i:0, Loop3
             BRA    Loop0

finished:
             AIS #2
    };
#else /* defined(__OPTIMIZE_FOR_SIZE__)  time optimized asm version. */
  asm {
#ifdef __HCS08__
             LDHX   _startupData.toCopyDownBeg:toCopyDownBegOffs
#else
             LDX    _startupData.toCopyDownBeg:(0+toCopyDownBegOffs)
             PSHX
             PULH
             LDX    _startupData.toCopyDownBeg:(1+toCopyDownBegOffs)
#endif
next:
             LDA   0,X    ; list is terminated by 2 zero bytes
             ORA   1,X
             BEQ copydone
             PSHX         ; store current position
             PSHH
             LDA   3,X    ; psh dest low
             PSHA
             LDA   2,X    ; psh dest high
             PSHA
             LDA   1,X    ; psh cnt low
             PSHA
             LDA   0,X    ; psh cnt high
             PSHA
             AIX   #4
             JSR  _COPY_L ; copy one block
             PULH
             PULX       
             TXA
             ADD   1,X    ; add low 
             PSHA 
             PSHH
             PULA
             ADC   0,X    ; add high
             PSHA
             PULH
             PULX
             AIX   #4
             BRA next
copydone:
  };
#endif /* defined(__OPTIMIZE_FOR_SIZE__) */

  
  /* FuncInits: for C++, this are the global constructors */
#ifdef __cplusplus
#ifdef __ELF_OBJECT_FILE_FORMAT__
  i = (int)(_startupData.nofInitBodies - 1);
  while (i >= 0) {
    (&_startupData.initBodies->initFunc)[i]();  /* call C++ constructors */
    i--;
  }
#else /* __ELF_OBJECT_FILE_FORMAT__ */
  /* HIWARE object file format */
  if (_startupData.mInits != NULL) {
    _PFunc *fktPtr;
    fktPtr = _startupData.mInits;
    while(*fktPtr != NULL) {
      (**fktPtr)(); /* call constructor */
      fktPtr++;
    }
  }
#endif /* __ELF_OBJECT_FILE_FORMAT__ */    
#endif /* __cplusplus */ 

  /* implement ROM libraries initialization here (see startup.c) */
}
#endif /* __ONLY_INIT_SP */

__EXTERN_C extern void main(void); /* prototype of main function */

#pragma NO_EXIT
__EXTERN_C void _Startup(void) { 
/* set the reset vector to _Startup in the linker parameter file (*.prm): 
    'VECTOR 0 _Startup'

    purpose:    1)  initialize the stack
                2)  initialize run-time, ...
                    initialize the RAM, copy down init dat etc (Init)
                3)  call main;
    called from: _PRESTART-code generated by the Linker
*/

  INIT_SP_FROM_STARTUP_DESC();
#ifndef  __ONLY_INIT_SP
  Init();
#endif
  __asm JMP main; /* with a C style main(); we would push the return address on the stack wasting 2 RAM bytes */
}
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