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#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#define VFLAG(...) if(vflag) print(__VA_ARGS__)
#define BIOSSEG(a) KADDR(((uint)(a))<<4)
#define UPTR2INT(p) ((uintptr)(p))
#define l16get(p) (((p)[1]<<8)|(p)[0])
#define l32get(p) (((u32int)l16get(p+2)<<16)|l16get(p))
static int vflag = 0;
typedef struct BIOS32sdh { /* BIOS32 Service Directory Header */
u8int signature[4]; /* "_32_" */
u8int physaddr[4]; /* physical address of entry point */
u8int revision;
u8int length; /* of header in paragraphs */
u8int checksum; /* */
u8int reserved[5];
} BIOS32sdh;
typedef struct BIOS32si { /* BIOS32 Service Interface */
u8int* base; /* base address of service */
int length; /* length of service */
u32int offset; /* service entry-point from base */
u16int ptr[3]; /* far pointer m16:32 */
} BIOS32si;
static Lock bios32lock;
static u16int bios32ptr[3];
static void* bios32entry;
int
bios32ci(BIOS32si* si, BIOS32ci* ci)
{
int r;
lock(&bios32lock);
r = bios32call(ci, si->ptr);
unlock(&bios32lock);
return r;
}
static void*
rsdchecksum(void* addr, int length)
{
u8int *p, sum;
sum = 0;
for(p = addr; length-- > 0; p++)
sum += *p;
if(sum == 0)
return addr;
return nil;
}
static void*
rsdscan(u8int* addr, int len, char* signature)
{
int sl;
u8int *e, *p;
e = addr+len;
sl = strlen(signature);
for(p = addr; p+sl < e; p += 16){
if(memcmp(p, signature, sl))
continue;
return p;
}
return nil;
}
static int
bios32locate(void)
{
uintptr ptr;
BIOS32sdh *sdh;
VFLAG("bios32link\n");
if((sdh = rsdscan(BIOSSEG(0xE000), 0x20000, "_32_")) == nil)
return -1;
if(rsdchecksum(sdh, sizeof(BIOS32sdh)) == nil)
return -1;
VFLAG("sdh @ %#p, entry %#ux\n", sdh, l32get(sdh->physaddr));
bios32entry = vmap(l32get(sdh->physaddr), 4096+1);
VFLAG("entry @ %#p\n", bios32entry);
ptr = UPTR2INT(bios32entry);
bios32ptr[0] = ptr & 0xffff;
bios32ptr[1] = (ptr>>16) & 0xffff;
bios32ptr[2] = KESEL;
VFLAG("bios32link: ptr %ux %ux %ux\n",
bios32ptr[0], bios32ptr[1], bios32ptr[2]);
return 0;
}
void
BIOS32close(BIOS32si* si)
{
vunmap(si->base, si->length);
free(si);
}
BIOS32si*
bios32open(char* id)
{
uint ptr;
BIOS32ci ci;
BIOS32si *si;
lock(&bios32lock);
if(bios32ptr[2] == 0 && bios32locate() < 0){
unlock(&bios32lock);
return nil;
}
VFLAG("bios32si: %s\n", id);
memset(&ci, 0, sizeof(BIOS32ci));
ci.eax = (id[3]<<24|(id[2]<<16)|(id[1]<<8)|id[0]);
bios32call(&ci, bios32ptr);
unlock(&bios32lock);
VFLAG("bios32si: eax %ux\n", ci.eax);
if(ci.eax & 0xff)
return nil;
VFLAG("bios32si: base %#ux length %#ux offset %#ux\n",
ci.ebx, ci.ecx, ci.edx);
if((si = malloc(sizeof(BIOS32si))) == nil)
return nil;
if((si->base = vmap(ci.ebx, ci.ecx)) == nil){
free(si);
return nil;
}
si->length = ci.ecx;
ptr = UPTR2INT(si->base)+ci.edx;
si->ptr[0] = ptr & 0xffff;
si->ptr[1] = (ptr>>16) & 0xffff;
si->ptr[2] = KESEL;
VFLAG("bios32si: eax entry %ux\n", ptr);
return si;
}
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