53 lines
983 B
C
53 lines
983 B
C
/*
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* mjs copyright
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*/
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/*
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* Obtain memory configuration information from the BIOS
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*
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* Note that we don't try too hard here; knowing the size of
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* base memory and extended memory out to 16 or 64M is enough for
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* the requirements of the bootstrap.
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*
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* We also maintain a pointer to the top of physical memory
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* once called to allow rangechecking of load/copy requests.
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*/
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#include <stand.h>
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#include "btxv86.h"
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vm_offset_t memtop;
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/*
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* Return base memory size in kB.
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*/
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int
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getbasemem(void)
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{
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v86.ctl = 0;
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v86.addr = 0x1a; /* int 0x12 */
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v86int();
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return(v86.eax & 0xffff);
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}
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/*
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* Return extended memory size in kB
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*/
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int
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getextmem(void)
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{
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int extkb;
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v86.ctl = 0;
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v86.addr = 0x15; /* int 0x12 function 0x88*/
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v86.eax = 0x8800;
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v86int();
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extkb = v86.eax & 0xffff;
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/* Set memtop to actual top or 16M, whicheve is less */
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memtop = min((0x100000 + (extkb * 1024)), (16 * 1024 * 1024));
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return(extkb);
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}
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