git.sur5r.net Git - cc65/blob - include/em.h

   1 /*****************************************************************************/
   2 /*                                                                           */
   3 /*                                   em.h                                    */
   4 /*                                                                           */
   5 /*                      API for extended memory access                       */
   6 /*                                                                           */
   7 /*                                                                           */
   8 /*                                                                           */
   9 /* (C) 2002      Ullrich von Bassewitz                                       */
  10 /*               Wacholderweg 14                                             */
  11 /*               D-70597 Stuttgart                                           */
  12 /* EMail:        uz@musoftware.de                                            */
  13 /*                                                                           */
  14 /*                                                                           */
  15 /* This software is provided 'as-is', without any expressed or implied       */
  16 /* warranty.  In no event will the authors be held liable for any damages    */
  17 /* arising from the use of this software.                                    */
  18 /*                                                                           */
  19 /* Permission is granted to anyone to use this software for any purpose,     */
  20 /* including commercial applications, and to alter it and redistribute it    */
  21 /* freely, subject to the following restrictions:                            */
  22 /*                                                                           */
  23 /* 1. The origin of this software must not be misrepresented; you must not   */
  24 /*    claim that you wrote the original software. If you use this software   */
  25 /*    in a product, an acknowledgment in the product documentation would be  */
  26 /*    appreciated but is not required.                                       */
  27 /* 2. Altered source versions must be plainly marked as such, and must not   */
  28 /*    be misrepresented as being the original software.                      */
  29 /* 3. This notice may not be removed or altered from any source              */
  30 /*    distribution.                                                          */
  31 /*                                                                           */
  32 /*****************************************************************************/
  33
  34
  35
  36 #ifndef _EM_H
  37 #define _EM_H
  38
  39
  40
  41 /*****************************************************************************/
  42 /*                                  Definitions                              */
  43 /*****************************************************************************/
  44
  45
  46
  47 /* Size of an extended memory page */
  48 #define EM_PAGE_SIZE          256
  49
  50 /* Error codes */
  51 #define EM_ERR_OK               0       /* No error */
  52 #define EM_ERR_NO_DRIVER        1       /* No driver available */
  53 #define EM_ERR_CANNOT_LOAD      2       /* Error loading driver */
  54 #define EM_ERR_INV_DRIVER       3       /* Invalid driver */
  55 #define EM_ERR_NO_DEVICE        4       /* Device (hardware) not found */
  56
  57 /* Parameters for the em_copy_... functions. NOTE: The first seven bytes
  58  * have the same order and alignment as needed for the Commodore REU, so
  59  * don't change the order without changing the assembler file that defines
  60  * the struct offsets and the code in the REU driver.
  61  */
  62 struct em_copy {
  63     void*           buf;        /* Memory buffer to copy from or to */
  64     unsigned char   offs;       /* Offset into page */
  65     unsigned        page;       /* Starting page to copy from or to */
  66     unsigned        count;      /* Number of bytes to copy */
  67     unsigned char   unused;     /* Make the size 8 bytes */
  68 };
  69
  70
  71
  72 /*****************************************************************************/
  73 /*                                 Functions                                 */
  74 /*****************************************************************************/
  75
  76
  77
  78 unsigned char __fastcall__ em_load_driver (const char* driver);
  79 /* Load an extended memory driver and return an error code */
  80
  81 unsigned char em_unload (void);
  82 /* Unload the currently loaded driver. */
  83
  84 unsigned em_pagecount (void);
  85 /* Return the total number of 256 byte pages available in extended memory. */
  86
  87 void* __fastcall__ em_map (unsigned page);
  88 /* Unmap the current page from memory and map a new one. The function returns
  89  * a pointer to the location of the page in memory. Note: Without calling
  90  * em_commit, the old contents of the memory window may be lost!
  91  */
  92
  93 void __fastcall__ em_commit (void);
  94 /* Commit changes in the memory window to extended storage. If the contents
  95  * of the memory window have been changed, these changes may be lost if
  96  * em_map, em_copyfrom or em_copyto are called without calling em_commit
  97  * first. Note: Not calling em_commit does not mean that the changes are
  98  * discarded, it does just mean that some drivers will discard the changes.
  99  */
 100
 101 void __fastcall__ em_copyfrom (const struct em_copy* copy_data);
 102 /* Copy from extended into linear memory. Note: This may invalidate the
 103  * currently mapped page.
 104  */
 105
 106 void __fastcall__ em_copyto (const struct em_copy* copy_data);
 107 /* Copy from linear into extended memory. Note: This may invalidate the
 108  * currently mapped page.
 109  */
 110
 111
 112
 113 /* End of em.h */
 114 #endif
 115
 116
 117