[syslinux] gpllib write_sectors() patch

[Don Hiatt]

Here is a partial patch that I'm using to illustrate a few questions
that I have.

Looking at the gpllib write_sectors (com32/gpllib/disk/write.c) it
looks like the allocated
size is wrong; size is in sectors so we should adjust the alloc/memcpy
by size*SECTOR.

Also, comparing core/diskio.c it looks like the registers aren't even
setup right.
In the patch below I put an #if 0 around the old code to demonstrate
how it differs
from diskio.c

I also added a call to get_drive_parameters() so that it would be like
the gpllib/read.c
However, it would probably be best to not have to call
get_drive_parameters every time
so they should be supplied in the driveinfo struct (for both read and write).

 /**
  * write_sectors - write several sectors from disk
@@ -37,9 +55,14 @@ int write_sectors(const struct driveinfo
*drive_info, const unsigned int lba,
 {
     com32sys_t inreg, outreg;
     struct ebios_dapa *dapa = __com32.cs_bounce;
-    void *buf = (char *)__com32.cs_bounce + size;
+    void *buf = (char *)__com32.cs_bounce + size*SECTOR;

-    memcpy(buf, data, size);
+    if (get_drive_parameters(drive_info) == -1) {
+      printf("ERR: Can't get drive params!\n");
+      return -1;
+    }
+
+    memcpy(buf, data, size*SECTOR);
     memset(&inreg, 0, sizeof inreg);

     if (drive_info->ebios) {
@@ -48,11 +71,17 @@ int write_sectors(const struct driveinfo
*drive_info, const unsigned int lba,
        dapa->off = OFFS(buf);
        dapa->seg = SEG(buf);
        dapa->lba = lba;
-
+#if 0
        inreg.esi.w[0] = OFFS(dapa);
        inreg.ds = SEG(dapa);
        inreg.edx.b[0] = drive_info->disk;
        inreg.eax.w[0] = 0x4300;        /* Extended write */
+#endif
+       inreg.eax.b[1] = 0x43;
+       inreg.edx.b[0] = drive_info->disk;
+       inreg.ds       = SEG(dapa);
+       inreg.esi.w[0] = OFFS(dapa);
+