/*
    MMDirectMapping.c, Copyright  (c) by George Fankhauser,
    Swiss Federal Institute of Technology,
    Computer Engineering and Networks Laboratory.

    TOPSY -- A Teachable Operating System.
             Implementation of a tiny and simple
             micro kernel for teaching purposes.

    For further information, please visit http://www.tik.ee.ethz.ch/~topsy

    This software is provided under the terms of the GNU General Public Licence.

    A full copy of the GNU GPL is provided in the file COPYING found in the 
    development root of Topsy.
*/
/*

*/

#include "MMMapping.h"
#include "Threads.h"
#include "Support.h"

#include "Unix.h"


unsigned int physBase;
unsigned int bootStackBottom;

Error   mmInitMemoryMapping(Address codeAddr, unsigned long int codeSize,
			    Address dataAddr, unsigned long int dataSize,
			    Address userLoadedInKernelAt)
{
#ifdef __svr4__

    stack_t ss;
    
    ss.ss_sp = (char*)(physBase + BOOTSTACKTOP); // setup exception stack
    ss.ss_size = BOOTSTACKSIZE;                 // size
    ss.ss_flags = 0;          			// currently not on this stack
    sigaltstack(&ss, NULL);
    
#elif linux


#else // BSD like

    struct sigstack ss;
    
    ss.ss_sp = (char*)(physBase + BOOTSTACKTOP); // setup exception stack
    ss.ss_onstack = FALSE;                 // currently not on this stack
    sigstack(&ss, NULL);
    
#endif    

    return MM_INITMEMORYMAPPINGOK;
}

Error mmMapPages(Page startPage, Page nOfPages, PageStatus pstat)
{
    return MM_MAPPAGESOK;
}


Error mmUnmapPages(Page startPage, Page nOfPages)
{
    return MM_UNMAPPAGESOK;
}


Error mmMovePage(Page from, Page to)
{
    /* direct mapped memory systems can only copy the page */
    byteCopy((Address)(to*LOGICALPAGESIZE), (Address)(from*LOGICALPAGESIZE), 
							    LOGICALPAGESIZE);
    zeroOut((Address)(from*LOGICALPAGESIZE), LOGICALPAGESIZE);
    return MM_MOVEPAGEOK;
} 


Error mmProtectPage(Page page, ProtectionMode pmode)
{
    /* direct mapped memory does nothing */
    return MM_PROTECTPAGEFAILED;
}


Error  mmAddressSpaceRange(AddressSpace space, Address* addressPtr,
					unsigned long int* sizePtr)
{
    if (space == KERNEL) {
    	*addressPtr = (Address)physBase;
	*sizePtr = (PHYSMEM-USERMEM);
    }
    else if (space == USER) {
    	*addressPtr = (Address)physBase + (PHYSMEM-USERMEM);
	*sizePtr = USERMEM;
    }
    else return MM_ADDRESSSPACERANGEFAILED;
    return MM_ADDRESSSPACERANGEOK;
}