fload.c

mips架构的bootloader,99左右的版本 但源代码现在没人更新了

/*************************************************************
 * File: mon/fload.c
 * Purpose: fast-format file loader
 * Author: Phil Bunce ([e-mail])
 * Revision History:
 *	970303	Start of revision history
 *	980404	Added DL_MFLAG
 */

#include <mon.h>

/*
 * Useful fast-records for testing purposes:
 *	/ACgAgAA	- addr = a0020000
 *	/ZAI		- clear 24 bytes
 *	/E		- define entry at 'addr' and exit
 *	AAABAAAC	- 00 00 01 00 00 02
 *	/Sfred,X	- symbol = 'addr'
 *	/BAB		- byte of 01
 */

#define MSK 0xff

Uchar exta = ',';
Uchar extb = '.';
Uchar extc = '/';

extern int chksum;
extern Ulong nextaddr;
extern int blksz;
extern int blkinx;

/*************************************************************
*  fload(rec,offset,plen,pFlags)
*	load a fast-mode record
*/
fload(rec,offset,plen,pFlags)
Uchar *rec;
Ulong offset;
int *plen,*pFlags;
{
int n,i,c,len,s,flags;
Uchar adat[8],name[LINESZ];
Uchar buf[3];
Ulong addr,zcnt,bdat,j;

flags = *pFlags;
*plen = 0;
s = 1;
for (len=0;;) {
	if (!getrec(adat,rec)) break;
	if (flags&DL_MFLAG && !(adat[0] == 'A' || adat[0] == 'S')) 
		continue; /* don't load memory */
	if (adat[0] == '/') {
		switch (adat[1]) {
		    case 'D' :  /* this is a driver */
			flags |= DL_DFLAG;
			break;
		    case 'K' :  /* klear checksum (sic) */
			chksum = 0;
			break;
		    case 'C' :  /* compare checksum */
			if (!getb64(&zcnt,&adat[2],-2)) return(-1);
			chksum &= 0xfff;
			if (!(flags&DL_IFLAG) && zcnt != chksum) return(-4);
			chksum = 0;
			break;
		    case 'Z' :  /* zero fill */
			if (!getb64(&zcnt,&adat[2],2)) return(-1);
			buf[0] = buf[1] = buf[2] = 0;
			for (i=0;i<zcnt;i++) {
				memwrite(buf,3,flags);
				len += 3;
				}
			break;
		    case 'B' :  /* byte */
			if (!getb64(&j,&adat[2],2)) return(-1);
			buf[0] = j;
			memwrite(buf,1,flags);
			len++;
			break;
		    case 'A' :  /* address */
			if (!getrec(&adat[4],rec)) return(-2);
			if (!getb64(&addr,&adat[2],6)) return(-1);
#if 0
			if (flags&DL_TFLAG && getGpr(7) == 0) {
				topClientMem -= addr;
				putGpr(29,clienttos());
				nextaddr = topClientMem;
				putGpr(7,topClientMem);
				}
			else nextaddr = addr+offset;
#else
			nextaddr = addr+offset;
#endif
			break;
		    case 'E' :  /* end */
			s = 0;
			if (flags&DL_DFLAG) break;
			putPc(nextaddr);
			break;
		    case 'S' :  /* symbol */
			i = 2;
			for (j=0;;) {
				c = adat[i++];
				/* chksum += c; */
				if (c == ',') break;
				name[j++] = c;
				if (i >= 4) {
					if (!getrec(adat,rec)) return(-2);
					i = 0;
					}
				}
			name[j] = 0;
			if (!(flags&DL_DFLAG)) /* ignore syms if driver */
				if (!newsym(name,nextaddr)) return(-5);
			break;
		    default : 
			return(-3);
		    	}
		}
	else {  /* data */
		if (!getb64(&bdat,&adat[0],4)) return(-1);
		for (i=2;i>=0;i--) {
			buf[i] = bdat&MSK;
			bdat>>= 8;
			}
		memwrite(buf,3,flags);
		len += 3;
		}
	}
*plen = len;
*pFlags = flags;
return(s);
}

/*************************************************************
*  getrec(p,curblk)
*	get the next 4-byte record (if there are any left)
*/
getrec(p,curblk)
Uchar *p,*curblk;
{
int i;

if (blkinx >= blksz) return(0);
for (i=0;i<4;i++) p[i] = curblk[blkinx++];
return(1);
}

/*************************************************************
*  memwrite(dat,n,flags)
*	write the data to memory
*/
memwrite(dat,n,flags)
Uchar *dat;
int n,flags;
{
int i;

for (i=0;i<n;i++) {
	if (flags&DL_DFLAG) store_byte(nextaddr++,dat[i]);
	else write_target(XT_MEM,nextaddr++,dat[i],1);
	}
}

/*************************************************************
*  getb64(vp,p,n)
*	get a number of base-64 digits
*	if n < 0 then don't add value to chksum.
*/
getb64(vp,p,n)
Ulong *vp;
Uchar *p;
int n;
{
Ulong v;
int c,i;

v = 0; *vp = 0;
for (i=0;i<((n<0)?0-n:n);i++) {
	v <<= 6;
	c = *p++;
	if (c >= 'A' && c <= 'Z') v |= c-'A';
	else if (c >= 'a' && c <= 'z') v |= c-'a'+26;
	else if (c >= '0' && c <= '9') v |= c-'0'+52;
	else if (c == exta) v |= 62; 
	else if (c == extb) v |= 63; 
	else return(0);
	}

switch (n) {
	case 6 : chksum += (v>>24)&0xfff;
	case 4 : chksum += (v>>12)&0xfff;
	case 2 : chksum += v&0xfff;
	}

*vp = v;
return(1);
}