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boot/pc: PBS now calculates rootdir offset itself

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ment 2011-06-08 23:04:30 +02:00
parent 474df96424
commit 748551ea06
1 changed files with 35 additions and 8 deletions
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43
sys/src/boot/pc/pbs.s
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@ -76,6 +76,7 @@ _start0x5A:
MTSR(rAX, rES)
LWI(0x100, rCX)
MW(rSI,rBX) /* address of partition record -> rBX */
LWI(RELOC, rSI)
MW(rSI, rSP)
LWI(_magic(SB), rDI)
@ -97,10 +98,38 @@ TEXT start16(SB), $0
STI
LWI(hello(SB), rSI)
CALL16(print16(SB))
LWI(crnl(SB), rSI)
CALL16(print16(SB))
LW(_volid(SB), rAX) /* Xrootlo */
LW(_volid+2(SB), rBX) /* Xroothi */
PUSHR(rDX)
PUSHR(rBX)
LB(_nfats(SB), rCL) /* # of fats */
LW(_fatsize(SB), rAX) /* fat size */
MUL(rCX) /* DX:AX = #sectors */
JNE _fatszok /* zero? it's FAT32 */
LW(_fatsz32+2(SB), rBX) /* hi word */
IMUL(rCX, rBX) /* ... in sectors */
LW(_fatsz32(SB), rAX) /* lo word */
MUL(rCX) /* ... in sectors */
ADD(rBX, rDX) /* DX:AX = #sectors */
_fatszok:
POPR(rBX) /* address of partition record */
LXW(8, xBX, rCX) /* lo partition LBA */
ADD(rCX, rAX)
LXW(10, xBX, rCX) /* hi partition LBA */
ADC(rCX, rDX)
CLR(rBX)
LW(_nresrv(SB), rCX) /* # of reserved */
ADD(rCX, rAX)
ADC(rDX, rBX)
SW(rAX, _volid(SB)) /* save for later use */
SW(rDX, _volid+2(SB))
POPR(rDX)
PUSHR(rBP)
LW(_sectsize(SB), rCX)
SUB(rCX, rSP)
@ -270,7 +299,5 @@ TEXT ioerror(SB), $0
BYTE $'e'; BYTE $'r'; BYTE $'r'; BYTE $0
TEXT hello(SB), $0
BYTE $'p'; BYTE $'b'; BYTE $'s'; BYTE $0
TEXT crnl(SB), $0
BYTE $'\r'; BYTE $'\n'; BYTE $0
BYTE $'p'; BYTE $'b'; BYTE $'s'; BYTE $'\r';
BYTE $'\n'; BYTE $0