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#include "mem.h"
/*
* Turn off MMU, then memmove the new kernel to its correct location
* in physical memory. Then jumps the to start of the kernel.
*/
TEXT main(SB),$0
MOVL p1+0(FP), DI /* destination */
MOVL DI, AX /* entry point */
MOVL p2+4(FP), SI /* source */
MOVL n+8(FP), CX /* byte count */
/*
* disable paging
*/
MOVL CR0, DX
ANDL $~0x80000000, DX /* ~(PG) */
MOVL DX, CR0
MOVL $0, DX
MOVL DX, CR3
/* stack below entry point */
MOVL AX, SP
/* park cpu for zero entry point */
ORL AX, AX
JZ _idle
/*
* the source and destination may overlap.
* determine whether to copy forward or backwards
*/
CMPL SI, DI
JGT _forward
MOVL SI, DX
ADDL CX, DX
CMPL DX, DI
JGT _back
_forward:
CLD
REP; MOVSB
JMP _startkernel
_back:
ADDL CX, DI
ADDL CX, SI
SUBL $1, DI
SUBL $1, SI
STD
REP; MOVSB
JMP _startkernel
/*
* JMP to kernel entry point. Note the true kernel entry point is
* the virtual address KZERO|AX, but this must wait until
* the MMU is enabled by the kernel in l.s
*/
_startkernel:
ORL AX, AX /* NOP: avoid link bug */
JMP* AX
_idle:
HLT
JMP _idle
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