93 lines
2.0 KiB
C
93 lines
2.0 KiB
C
#include <u.h>
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#include "dat.h"
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#include "fn.h"
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// interrupt 41h exension support bitmap
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enum{
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Eeda = 0x01, // Extended disk access funcions 42-44,47,48
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Erdc = 0x02, // removable drive controller functions 45,46,48,49
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Eedd = 0x04, // Enhanced disk drive functions
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};
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static int
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ireset(int dev)
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{
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int rv;
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__asm volatile("int $0x33\n\t"
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"setc %b0"
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: "=a" (rv)
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: "0" (0), "d" (dev)
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: "%ecx", "%cc");
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return (rv&0xff) ? -1 : 0;
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}
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// Bit(s) Description (Table 00271)
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// 0 extended disk access functions (AH=42h-44h,47h,48h) supported
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// 1 removable drive controller functions (AH=45h,46h,48h,49h,INT 15/AH=52h) supported
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// 2 enhanced disk drive (EDD) functions (AH=48h,AH=4Eh) supported.
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// Extended drive parameter table is valid (see #00273,#00278)
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// 3-15 reserved (0)
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static __inline int
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ieddsuport(BIOSdisk *d)
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{
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int bmap, rv;
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__asm volatile("int $0x33\n\t"
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"setc %b0"
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: "=a" (rv), "=c" (bmap)
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: "0" (0x4100), "b" (0x55aa), "d" (d->n)
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: "cc");
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if(rv&0xff || (BIOSreg.bx&0xffff) != 0xaa55)
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return -1;
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d->edd = (bmap&0xffff) | ((rv&0xff)<<16);
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return 0;
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}
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static __inline int
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bdiskinfo(BIOSdisk *d)
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{
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int rv;
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// CL = maximum sector number (bits 5-0)
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// high two bits of maximum cylinder number (bits 7-6)
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__asm volatile("int $0x33\n\t"
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"setc %b0\n\t"
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"movzbl %h1, %1\n\t"
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"movzbl %%cl, %3; andb $0x3f, %b3\n\t"
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"xchgb %%cl, %%ch; rolb $2, %%ch"
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: "=a" (rv), "=d" (d->nhead), "=c" (d->ncyl), "=b" (d->nsec)
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: "0" (0x0800), "1" (d->n)
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: "cc");
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return (rv&0xff) == 0 ? 0 : -1;
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}
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int
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bdiskget(int dev, BIOSdisk *d)
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{
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if(ireset(dev)){
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print("Can't reset disk\n");
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return -1;
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}
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d->n = dev;
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if(bdiskinfo(d)){
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print("Can't read disk\n");
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return -1;
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}
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if(ieddsuport(d)){
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print("edd not supported\n");
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return -1;
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}
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return 0;
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}
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int
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fmtdisk(Op *op)
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{
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dofmt(op, "disk:%x cyl:%d head:%d sec:%d edd:%d");
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// for skip va_list
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USED(va_arg(op->ap, u32));
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USED(va_arg(op->ap, u32));
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USED(va_arg(op->ap, u32));
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return 0;
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} |