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SCP: Avoid writing out memory buffered devices on detach that haven't changed

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As discussed in #1109
This commit is contained in:
Mark Pizzolato 2022-02-13 22:50:37 -08:00
parent 0116987fc7
commit 315a07cbc7
2 changed files with 18 additions and 5 deletions
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22
scp.c
View file

@ -8143,13 +8143,22 @@ else {
}
if (uptr->flags & UNIT_BUFABLE) { /* buffer? */
uint32 cap = ((uint32) uptr->capac) / dptr->aincr; /* effective size */
if (uptr->flags & UNIT_MUSTBUF) /* dyn alloc? */
if (uptr->flags & UNIT_MUSTBUF) { /* dyn alloc? */
uptr->filebuf = calloc (cap, SZ_D (dptr)); /* allocate */
if (uptr->filebuf == NULL) /* no buffer? */
return attach_err (uptr, SCPE_MEM); /* error */
uptr->filebuf2 = calloc (cap, SZ_D (dptr)); /* allocate copy */
if ((uptr->filebuf == NULL) || /* no buffer? */
(uptr->filebuf2 == NULL)) {
free (uptr->filebuf);
uptr->filebuf = NULL;
free (uptr->filebuf2);
uptr->filebuf2 = NULL;
return attach_err (uptr, SCPE_MEM); /* error */
}
}
sim_messagef (SCPE_OK, "%s: buffering file in memory\n", sim_uname (uptr));
uptr->hwmark = (uint32)sim_fread (uptr->filebuf, /* read file */
SZ_D (dptr), cap, uptr->fileref);
memcpy (uptr->filebuf2, uptr->filebuf, cap * SZ_D (dptr));/* save initial contents */
uptr->flags = uptr->flags | UNIT_BUF; /* set buffered */
}
uptr->flags = uptr->flags | UNIT_ATT;
@ -8268,7 +8277,8 @@ if ((dptr = find_dev_from_unit (uptr)) == NULL)
return SCPE_OK;
if ((uptr->flags & UNIT_BUF) && (uptr->filebuf)) {
uint32 cap = (uptr->hwmark + dptr->aincr - 1) / dptr->aincr;
if (uptr->hwmark && ((uptr->flags & UNIT_RO) == 0)) {
if (((uptr->flags & UNIT_RO) == 0) &&
(memcmp (uptr->filebuf, uptr->filebuf2, (size_t)(SZ_D (dptr) * (uptr->capac / dptr->aincr))) != 0)) {
sim_messagef (SCPE_OK, "%s: writing buffer to file: %s\n", sim_uname (uptr), uptr->filename);
rewind (uptr->fileref);
sim_fwrite (uptr->filebuf, SZ_D (dptr), cap, uptr->fileref);
@ -8276,8 +8286,10 @@ if ((uptr->flags & UNIT_BUF) && (uptr->filebuf)) {
sim_printf ("%s: I/O error - %s", sim_uname (uptr), strerror (errno));
}
if (uptr->flags & UNIT_MUSTBUF) { /* dyn alloc? */
free (uptr->filebuf); /* free buf */
free (uptr->filebuf); /* free buffers */
uptr->filebuf = NULL;
free (uptr->filebuf2);
uptr->filebuf2 = NULL;
}
uptr->flags = uptr->flags & ~UNIT_BUF;
}

1
sim_defs.h
View file

@ -585,6 +585,7 @@ struct UNIT {
uint32 dynflags; /* dynamic flags */
t_addr capac; /* capacity */
t_addr pos; /* file position */
void *filebuf2; /* copy of initial memory buffer */
void (*io_flush)(UNIT *up); /* io flush routine */
uint32 iostarttime; /* I/O start time */
int32 buf; /* buffer */