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