sdcc/device/lib/_gptrgetc.c

   1 /*-------------------------------------------------------------------------
   2    _gptrgetc.c - get value for a generic pointer (used with --xram-movc)
   3
   4    Copyright (c) 1999, Sandeep Dutta . sandeep.dutta@usa.net
   5
   6    This library is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by the
   8    Free Software Foundation; either version 2, or (at your option) any
   9    later version.
  10
  11    This library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this library; see the file COPYING. If not, write to the
  18    Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  19    MA 02110-1301, USA.
  20
  21    As a special exception, if you link this library with other files,
  22    some of which are compiled with SDCC, to produce an executable,
  23    this library does not by itself cause the resulting executable to
  24    be covered by the GNU General Public License. This exception does
  25    not however invalidate any other reasons why the executable file
  26    might be covered by the GNU General Public License.
  27 -------------------------------------------------------------------------*/
  28
  29
  30 /* the  return value is expected to be in acc, and not in the standard
  31  * location dpl. Therefore we choose return type void here: */
  32
  33 #if 1
  34
  35 void
  36 _gptrgetc (char *gptr) __naked
  37 {
  38 /* This is the new version with pointers up to 16 bits.
  39    B cannot be trashed */
  40
  41     gptr; /* hush the compiler */
  42
  43     __asm
  44     ;   save values passed
  45     ;
  46     ;   depending on the pointer type acc. to SDCCsymt.h
  47     ;
  48         jb              _B_7,codeptr$        ; >0x80 code               ; 3
  49         jnb             _B_6,xdataptr$       ; <0x40 far                ; 3
  50
  51         mov     dph,r0 ; save r0 independent of regbank ; 2
  52         mov     r0,dpl ; use only low order address             ; 2
  53
  54         jb              _B_5,pdataptr$       ; >0x60 pdata              ; 3
  55     ;
  56     ;   Pointer to data space
  57     ;
  58         mov     a,@r0                                                                   ; 1
  59         mov     r0,dph ; restore r0                                             ; 2
  60         mov     dph,#0 ; restore dph                                    ; 2
  61         ret                                                                                             ; 1
  62     ;
  63     ;   pointer to external stack or pdata
  64     ;
  65  pdataptr$:
  66         movx    a,@r0                                                                   ; 1
  67         mov     r0,dph ; restore r0                                             ; 2
  68         mov     dph,#0 ; restore dph                                    ; 2
  69         ret                                                                                             ; 1
  70 ;
  71 ;   pointer to xternal data
  72 ;   pointer to code area
  73 ;
  74  codeptr$:
  75  xdataptr$:
  76         clr     a                                                                               ; 1
  77         movc    a,@a+dptr                                                               ; 1
  78         ret                                                                                             ; 1
  79                                                                                                         ;===
  80                                                                                                         ;28 bytes
  81      __endasm;
  82 }
  83
  84 #else
  85
  86 void
  87 _gptrgetc (char *gptr) __naked
  88 {
  89     gptr; /* hush the compiler */
  90
  91     __asm
  92     ;   save values passed
  93         xch    a,r0
  94         push   acc
  95     ;
  96     ;   depending on the pointer type acc. to SDCCsymt.h
  97     ;
  98         mov     a,b
  99         jz      00001$  ; 0 near
 100         dec     a
 101         jz      00003$  ; 1 far
 102         dec     a
 103         jz      00003$  ; 2 code
 104         dec     a
 105         jz      00004$  ; 3 pdata
 106         dec     a       ; 4 skip generic pointer
 107         dec     a
 108         jz      00001$  ; 5 idata
 109     ;
 110     ;   any other value for type
 111     ;   return xFF
 112         mov     a,#0xff
 113         ret
 114     ;
 115     ;   Pointer to data space
 116     ;
 117  00001$:
 118         mov     r0,dpl     ; use only low order address
 119         mov     a,@r0
 120         ret
 121 ;
 122 ;   pointer to xternal data
 123 ;   pointer to code area
 124 ;
 125  00003$:
 126         ; clr     a  is already 0
 127         movc    a,@a+dptr
 128         ret
 129 ;
 130 ;   pointer to xternal stack
 131 ;
 132  00004$:
 133         mov     r0,dpl
 134         movx    a,@r0
 135 ;
 136 ;   restore and return
 137 ;
 138         mov     r0,a
 139         pop     acc
 140         xch     a,r0
 141         ret
 142      __endasm;
 143
 144 }
 145 #endif