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authorH. Peter Anvin <hpa@zytor.com>2009-03-16 19:05:03 -0700
committerH. Peter Anvin <hpa@zytor.com>2009-03-16 19:06:42 -0700
commit6ab875d0d2316c8d6649f137b3e28405d5244f95 (patch)
tree2ee2171bef83c875f56a53a4b4950995d1689e5b /memdisk
parent42f15f93323394f502645264b4809b031a9b4442 (diff)
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memdisk: move the floppy disk geometry code in parallel with the MBR code
Move the floppy disk geometry generation code into parallel with the MBR code, which pretty much mimics the previous behavior.
Diffstat (limited to 'memdisk')
-rw-r--r--memdisk/setup.c165
1 files changed, 81 insertions, 84 deletions
diff --git a/memdisk/setup.c b/memdisk/setup.c
index e3804358..db644ae2 100644
--- a/memdisk/setup.c
+++ b/memdisk/setup.c
@@ -444,7 +444,7 @@ const struct geometry *get_disk_image_geometry(uint32_t where, uint32_t size)
{
static struct geometry hd_geometry;
struct dosemu_header dosemu;
- unsigned int sectors, v;
+ unsigned int sectors, xsectors, v;
unsigned int offset;
int i;
const char *p;
@@ -455,55 +455,7 @@ const struct geometry *get_disk_image_geometry(uint32_t where, uint32_t size)
if ( CMD_HASDATA(p = getcmditem("offset")) && (v = atou(p)) )
offset = v;
- sectors = (size-offset) >> 9;
-
- if (sectors < 4096*2) {
- int ok = 0;
- unsigned int xsectors = sectors;
-
- while (!ok) {
- /* Assume it's a floppy drive, guess a geometry */
- unsigned int type, track;
- int c, h, s;
-
- if (xsectors < 320*2) {
- c = 40; h = 1; type = 1;
- } else if (xsectors < 640*2) {
- c = 40; h = 2; type = 1;
- } else if (xsectors < 1200*2) {
- c = 80; h = 2; type = 3;
- } else if (xsectors < 1440*2) {
- c = 80; h = 2; type = 2;
- } else if (xsectors < 2880*2) {
- c = 80; h = 2; type = 4;
- } else {
- c = 80; h = 2; type = 6;
- }
- track = c*h;
- while (c < 256) {
- s = xsectors/track;
- if (s < 63 && (xsectors % track) == 0) {
- ok = 1;
- break;
- }
- c++;
- track += h;
- }
- if (ok) {
- hd_geometry.driveno = 0;
- hd_geometry.c = c;
- hd_geometry.h = h;
- hd_geometry.s = s;
- } else {
- /* No valid floppy geometry, fake it by simulating broken
- sectors at the end of the image... */
- xsectors++;
- }
- }
- } else {
- /* Hard disk */
- hd_geometry.driveno = 0x80;
- }
+ sectors = xsectors = (size-offset) >> 9;
hd_geometry.sectors = sectors;
hd_geometry.offset = offset;
@@ -528,12 +480,13 @@ const struct geometry *get_disk_image_geometry(uint32_t where, uint32_t size)
if ( CMD_HASDATA(p = getcmditem("s")) && (v = atou(p)) )
hd_geometry.s = v;
- if ( !hd_geometry.c || !hd_geometry.h || !hd_geometry.s ) {
+ if ( !hd_geometry.h || !hd_geometry.s ) {
int h, s, max_h, max_s;
- max_h = max_s = 0;
+ max_h = hd_geometry.h;
+ max_s = hd_geometry.s;
- if (!max_h && !max_s) {
+ if (!(max_h|max_s)) {
/* Look for a FAT superblock and if we find something that looks
enough like one, use geometry from that. This takes care of
megafloppy images and unpartitioned hard disks. */
@@ -560,45 +513,89 @@ const struct geometry *get_disk_image_geometry(uint32_t where, uint32_t size)
}
}
- if (!max_h && !max_s) {
- /* Not FAT, assume it is a hard disk image and scan for a
- partition table */
- const struct ptab_entry *ptab = (const struct ptab_entry *)
- ((char *)where+hd_geometry.offset+(512-2-4*16));
-
- if (*(uint16_t *)((char *)where+512) == 0xaa55)
- for ( i = 0 ; i < 4 ; i++ ) {
- if ( ptab[i].type && !(ptab[i].active & 0x7f) ) {
- s = (ptab[i].start_s & 0x3f);
- h = ptab[i].start_h + 1;
-
- if ( max_h < h ) max_h = h;
- if ( max_s < s ) max_s = s;
-
- s = (ptab[i].end_s & 0x3f);
- h = ptab[i].end_h + 1;
-
- if ( max_h < h ) max_h = h;
- if ( max_s < s ) max_s = s;
-
- hd_geometry.driveno = 0x80; /* Assume hard disk */
+ if (!(max_h|max_s)) {
+ /* No FAT filesystem found to steal geometry from... */
+ if (sectors < 4096*2) {
+ int ok = 0;
+ unsigned int xsectors = sectors;
+
+ hd_geometry.driveno = 0; /* Assume floppy */
+
+ while (!ok) {
+ /* Assume it's a floppy drive, guess a geometry */
+ unsigned int type, track;
+ int c, h, s;
+
+ if (xsectors < 320*2) {
+ c = 40; h = 1; type = 1;
+ } else if (xsectors < 640*2) {
+ c = 40; h = 2; type = 1;
+ } else if (xsectors < 1200*2) {
+ c = 80; h = 2; type = 3;
+ } else if (xsectors < 1440*2) {
+ c = 80; h = 2; type = 2;
+ } else if (xsectors < 2880*2) {
+ c = 80; h = 2; type = 4;
+ } else {
+ c = 80; h = 2; type = 6;
+ }
+ track = c*h;
+ while (c < 256) {
+ s = xsectors/track;
+ if (s < 63 && (xsectors % track) == 0) {
+ ok = 1;
+ break;
+ }
+ c++;
+ track += h;
+ }
+ if (ok) {
+ max_h = h;
+ max_s = s;
+ } else {
+ /* No valid floppy geometry, fake it by simulating broken
+ sectors at the end of the image... */
+ xsectors++;
}
}
+ } else {
+ /* Assume it is a hard disk image and scan for a partition table */
+ const struct ptab_entry *ptab = (const struct ptab_entry *)
+ ((char *)where+hd_geometry.offset+(512-2-4*16));
+
+ hd_geometry.driveno = 0x80; /* Assume hard disk */
+
+ if (*(uint16_t *)((char *)where+512) == 0xaa55)
+ for ( i = 0 ; i < 4 ; i++ ) {
+ if ( ptab[i].type && !(ptab[i].active & 0x7f) ) {
+ s = (ptab[i].start_s & 0x3f);
+ h = ptab[i].start_h + 1;
+
+ if ( max_h < h ) max_h = h;
+ if ( max_s < s ) max_s = s;
+
+ s = (ptab[i].end_s & 0x3f);
+ h = ptab[i].end_h + 1;
+
+ if ( max_h < h ) max_h = h;
+ if ( max_s < s ) max_s = s;
+ }
+ }
+ }
}
if (!max_h)
- max_h = sectors > 2097152 ? 255 : 64;
+ max_h = xsectors > 2097152 ? 255 : 64;
if (!max_s)
- max_s = sectors > 2097152 ? 63 : 32;
-
- if ( !hd_geometry.h )
- hd_geometry.h = max_h;
- if ( !hd_geometry.s )
- hd_geometry.s = max_s;
- if ( !hd_geometry.c )
- hd_geometry.c = sectors/(hd_geometry.h*hd_geometry.s);
+ max_s = xsectors > 2097152 ? 63 : 32;
+
+ hd_geometry.h = max_h;
+ hd_geometry.s = max_s;
}
+ if ( !hd_geometry.c )
+ hd_geometry.c = xsectors/(hd_geometry.h*hd_geometry.s);
+
if ( (p = getcmditem("floppy")) != CMD_NOTFOUND ) {
hd_geometry.driveno = CMD_HASDATA(p) ? atou(p) & 0x7f : 0;
} else if ( (p = getcmditem("harddisk")) != CMD_NOTFOUND ) {