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#include "u.h"
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#include "../port/lib.h"
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#include "mem.h"
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#include "dat.h"
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#include "fns.h"
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#include "io.h"
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#define VFLAG(...)	if(vflag) print(__VA_ARGS__)
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#define UPTR2INT(p)	((uintptr)(p))
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static int vflag = 0;
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typedef struct BIOS32sdh {		/* BIOS32 Service Directory Header */
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	u8int	signature[4];		/* "_32_" */
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	u8int	physaddr[4];		/* physical address of entry point */
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	u8int	revision;
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	u8int	length;			/* of header in paragraphs */
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	u8int	checksum;		/* */
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	u8int	reserved[5];
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} BIOS32sdh;
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typedef struct BIOS32si {		/* BIOS32 Service Interface */
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	u8int*	base;			/* base address of service */
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	int	length;			/* length of service */
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	u32int	offset;			/* service entry-point from base */
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	u16int	ptr[3];			/* far pointer m16:32 */
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} BIOS32si;
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static Lock bios32lock;
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static u16int bios32ptr[3];
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static void* bios32entry;
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int
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bios32ci(BIOS32si* si, BIOS32ci* ci)
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{
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	int r;
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	lock(&bios32lock);
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	r = bios32call(ci, si->ptr);
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	unlock(&bios32lock);
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	return r;
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}
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static void*
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rsdchecksum(void* addr, int length)
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{
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	u8int *p, sum;
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	sum = 0;
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	for(p = addr; length-- > 0; p++)
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		sum += *p;
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	if(sum == 0)
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		return addr;
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	return nil;
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}
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static void*
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rsdscan(u8int* addr, int len, char* signature)
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{
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	int sl;
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	u8int *e, *p;
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	e = addr+len;
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	sl = strlen(signature);
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	for(p = addr; p+sl < e; p += 16){
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		if(memcmp(p, signature, sl))
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			continue;
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		return p;
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	}
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	return nil;
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}
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static int
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bios32locate(void)
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{
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	uintptr ptr;
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	BIOS32sdh *sdh;
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	VFLAG("bios32link\n");
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	if((sdh = rsdscan(BIOSSEG(0xE000), 0x20000, "_32_")) == nil)
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		return -1;
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	if(rsdchecksum(sdh, sizeof(BIOS32sdh)) == nil)
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		return -1;
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	VFLAG("sdh @ %#p, entry %#ux\n", sdh, L32GET(sdh->physaddr));
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	bios32entry = vmap(L32GET(sdh->physaddr), 4096+1);
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	VFLAG("entry @ %#p\n", bios32entry);
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	ptr = UPTR2INT(bios32entry);
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	bios32ptr[0] = ptr & 0xffff;
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	bios32ptr[1] = (ptr>>16) & 0xffff;
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	bios32ptr[2] = KESEL;
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	VFLAG("bios32link: ptr %ux %ux %ux\n",
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		bios32ptr[0], bios32ptr[1], bios32ptr[2]);
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	return 0;
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}
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void
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BIOS32close(BIOS32si* si)
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{
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	vunmap(si->base, si->length);
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	free(si);
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}
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BIOS32si*
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bios32open(char* id)
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{
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	uint ptr;
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	BIOS32ci ci;
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	BIOS32si *si;
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	lock(&bios32lock);
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	if(bios32ptr[2] == 0 && bios32locate() < 0){
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		unlock(&bios32lock);
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		return nil;
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	}
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	VFLAG("bios32si: %s\n", id);
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	memset(&ci, 0, sizeof(BIOS32ci));
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	ci.eax = (id[3]<<24|(id[2]<<16)|(id[1]<<8)|id[0]);
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	bios32call(&ci, bios32ptr);
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	unlock(&bios32lock);
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	VFLAG("bios32si: eax %ux\n", ci.eax);
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	if(ci.eax & 0xff)
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		return nil;
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	VFLAG("bios32si: base %#ux length %#ux offset %#ux\n",
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		ci.ebx, ci.ecx, ci.edx);
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	if((si = malloc(sizeof(BIOS32si))) == nil)
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		return nil;
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	if((si->base = vmap(ci.ebx, ci.ecx)) == nil){
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		free(si);
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		return nil;
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	}
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	si->length = ci.ecx;
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	ptr = UPTR2INT(si->base)+ci.edx;
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	si->ptr[0] = ptr & 0xffff;
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	si->ptr[1] = (ptr>>16) & 0xffff;
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	si->ptr[2] = KESEL;
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	VFLAG("bios32si: eax entry %ux\n", ptr);
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	return si;
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}