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96 lines
1.8 KiB
96 lines
1.8 KiB
/*[
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verw.c
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LOCAL CHAR SccsID[]="@(#)verw.c 1.5 02/09/94";
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VERW CPU Functions.
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-------------------
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]*/
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#include <insignia.h>
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#include <host_def.h>
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#include <xt.h>
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#include <c_main.h>
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#include <c_addr.h>
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#include <c_bsic.h>
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#include <c_prot.h>
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#include <c_seg.h>
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#include <c_stack.h>
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#include <c_xcptn.h>
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#include <c_reg.h>
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#include <verw.h>
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#include <c_page.h>
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/*
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=====================================================================
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EXTERNAL ROUTINES START HERE
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=====================================================================
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*/
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GLOBAL VOID
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VERW
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IFN1(
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IU32, op1 /* src(selector) operand */
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)
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{
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BOOL writeable = FALSE;
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IU32 descr;
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IU8 AR;
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if ( !selector_outside_GDT_LDT((IU16)op1, &descr) )
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{
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/* get access rights */
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AR = spr_read_byte(descr+5);
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switch ( descriptor_super_type((IU16)AR) )
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{
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case INVALID:
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case AVAILABLE_TSS:
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case LDT_SEGMENT:
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case BUSY_TSS:
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case CALL_GATE:
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case TASK_GATE:
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case INTERRUPT_GATE:
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case TRAP_GATE:
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case XTND_AVAILABLE_TSS:
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case XTND_BUSY_TSS:
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case XTND_CALL_GATE:
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case XTND_INTERRUPT_GATE:
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case XTND_TRAP_GATE:
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case CONFORM_NOREAD_CODE:
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case CONFORM_READABLE_CODE:
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case NONCONFORM_NOREAD_CODE:
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case NONCONFORM_READABLE_CODE:
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case EXPANDUP_READONLY_DATA:
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case EXPANDDOWN_READONLY_DATA:
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break; /* never writeable */
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case EXPANDUP_WRITEABLE_DATA:
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case EXPANDDOWN_WRITEABLE_DATA:
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/* access depends on privilege, it is required that
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DPL >= CPL and DPL >= RPL */
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if ( GET_AR_DPL(AR) >= GET_CPL() &&
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GET_AR_DPL(AR) >= GET_SELECTOR_RPL(op1) )
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writeable = TRUE;
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break;
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}
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}
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if ( writeable )
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{
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SET_ZF(1);
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}
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else
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{
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SET_ZF(0);
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}
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}
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