diff options
| -rw-r--r-- | sys/src/boot/pc/pbs.s | 43 |
1 files changed, 35 insertions, 8 deletions
diff --git a/sys/src/boot/pc/pbs.s b/sys/src/boot/pc/pbs.s index 6b11eded9..07c189e1c 100644 --- a/sys/src/boot/pc/pbs.s +++ b/sys/src/boot/pc/pbs.s @@ -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 |