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/*****************************************************************************/
/* */
/* em.h */
/* */
/* API for extended memory access */
/* */
/* */
/* */
/* (C) 2002-2012, Ullrich von Bassewitz */
/* Roemerstrasse 52 */
/* D-70794 Filderstadt */
/* EMail: uz@cc65.org */
/* */
/* */
/* This software is provided 'as-is', without any expressed or implied */
/* warranty. In no event will the authors be held liable for any damages */
/* arising from the use of this software. */
/* */
/* Permission is granted to anyone to use this software for any purpose, */
/* including commercial applications, and to alter it and redistribute it */
/* freely, subject to the following restrictions: */
/* */
/* 1. The origin of this software must not be misrepresented; you must not */
/* claim that you wrote the original software. If you use this software */
/* in a product, an acknowledgment in the product documentation would be */
/* appreciated but is not required. */
/* 2. Altered source versions must be plainly marked as such, and must not */
/* be misrepresented as being the original software. */
/* 3. This notice may not be removed or altered from any source */
/* distribution. */
/* */
/*****************************************************************************/
#ifndef _EM_H
#define _EM_H
/*****************************************************************************/
/* Definitions */
/*****************************************************************************/
/* Size of an extended memory page */
#define EM_PAGE_SIZE 256
/* Error codes */
#define EM_ERR_OK 0 /* No error */
#define EM_ERR_NO_DRIVER 1 /* No driver available */
#define EM_ERR_CANNOT_LOAD 2 /* Error loading driver */
#define EM_ERR_INV_DRIVER 3 /* Invalid driver */
#define EM_ERR_NO_DEVICE 4 /* Device (hardware) not found */
#define EM_ERR_INSTALLED 5 /* A driver is already installed */
/* Parameters for the em_copy_... functions. NOTE: The first seven bytes
** have the same order and alignment as needed for the Commodore REU, so
** don't change the order without changing the assembler file that defines
** the struct offsets and the code in the REU driver.
*/
struct em_copy {
void* buf; /* Memory buffer to copy from or to */
unsigned char offs; /* Offset into page */
unsigned page; /* Starting page to copy from or to */
unsigned count; /* Number of bytes to copy */
unsigned char unused; /* Make the size 8 bytes */
};
/*****************************************************************************/
/* Functions */
/*****************************************************************************/
unsigned char __fastcall__ em_load_driver (const char* driver);
/* Load and install an extended memory driver. Return an error code. */
unsigned char em_unload (void);
/* Uninstall, then unload the currently loaded driver. */
unsigned char __fastcall__ em_install (void* driver);
/* Install an already loaded driver. Return an error code. */
unsigned char em_uninstall (void);
/* Uninstall the currently loaded driver and return an error code.
** Note: This call does not free allocated memory.
*/
unsigned em_pagecount (void);
/* Return the total number of 256 byte pages available in extended memory. */
void* __fastcall__ em_map (unsigned page);
/* Unmap the current page from memory and map a new one. The function returns
** a pointer to the location of the page in memory. Note: Without calling
** em_commit, the old contents of the memory window may be lost!
*/
void* __fastcall__ em_use (unsigned page);
/* Tell the driver that the memory window is associated with a given page.
** This call is very similar to em_map. The difference is that the driver
** does not necessarily transfer the current contents of the extended
** memory into the returned window. If you're going to just write to the
** window and the current contents of the window are invalid or no longer
** use, this call may perform better than em_map.
*/
void em_commit (void);
/* Commit changes in the memory window to extended storage. If the contents
** of the memory window have been changed, these changes may be lost if
** em_map, em_copyfrom or em_copyto are called without calling em_commit
** first. Note: Not calling em_commit does not mean that the changes are
** discarded, it does just mean that some drivers will discard the changes.
*/
void __fastcall__ em_copyfrom (const struct em_copy* copy_data);
/* Copy from extended into linear memory. Note: This may invalidate the
** currently mapped page.
*/
void __fastcall__ em_copyto (const struct em_copy* copy_data);
/* Copy from linear into extended memory. Note: This may invalidate the
** currently mapped page.
*/
/* End of em.h */
#endif
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