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TAPE: Fix P7B reverse read logic for large records

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The earlier optimization to address P7B reverse read performance
didn't properly back up under some circumstances.

As potentially reported in #707
This commit is contained in:
Mark Pizzolato 2019-06-08 13:52:27 -07:00
parent 53ad66f57e
commit 09bbcb29d2
1 changed files with 13 additions and 8 deletions
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21
sim_tape.c
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@ -790,8 +790,9 @@ switch (f) { /* case on format */
uptr->hwmark = 0; uptr->hwmark = 0;
uptr->recsize = 0; uptr->recsize = 0;
uptr->tape_eom = 0; uptr->tape_eom = 0;
uptr->pos = 0;
sim_tape_rewind (uptr); MT_CLR_PNU (uptr);
MT_CLR_INMRK (uptr); /* Not within an AWS or TAR tapemark */
free (uptr->tape_ctx); free (uptr->tape_ctx);
uptr->tape_ctx = NULL; uptr->tape_ctx = NULL;
uptr->io_flush = NULL; uptr->io_flush = NULL;
@ -1472,19 +1473,19 @@ else switch (f) { /* otherwise the read me
if (1) { if (1) {
#define BUF_SZ 512 #define BUF_SZ 512
uint8 buf[BUF_SZ]; uint8 buf[BUF_SZ];
t_addr buf_offset; t_addr buf_offset = uptr->pos;
size_t bytes_in_buf = 0; size_t bytes_in_buf = 0;
size_t read_size; size_t read_size;
for (sbc = 1, all_eof = 1; (t_addr) sbc <= uptr->pos ; sbc++) { for (sbc = 1, all_eof = 1; (t_addr) sbc <= uptr->pos ; sbc++) {
if (bytes_in_buf == 0) { /* Need to Fill Buffer */ if (bytes_in_buf == 0) { /* Need to Fill Buffer */
if (uptr->pos < BUF_SZ) { if (buf_offset < BUF_SZ) {
read_size = (size_t)buf_offset;
buf_offset = 0; buf_offset = 0;
read_size = (size_t)uptr->pos;
} }
else { else {
buf_offset = uptr->pos - (sbc - 1 + BUF_SZ);
read_size = BUF_SZ; read_size = BUF_SZ;
buf_offset -= BUF_SZ;
} }
(void)sim_tape_seek (uptr, buf_offset); (void)sim_tape_seek (uptr, buf_offset);
bytes_in_buf = sim_fread (buf, sizeof (uint8), read_size, uptr->fileref); bytes_in_buf = sim_fread (buf, sizeof (uint8), read_size, uptr->fileref);
@ -3905,7 +3906,8 @@ static void ansi_make_HDR1 (HDR1 *hdr1, VOL1 *vol, HDR4 *hdr4, const char *filen
char extra_name_used[3] = "00"; char extra_name_used[3] = "00";
char *fn_cpy, *c, *ext; char *fn_cpy, *c, *ext;
stat (filename, &statb); memset (&statb, 0, sizeof (statb));
(void)stat (filename, &statb);
if (!(fn = strrchr (filename, '/')) && !(fn = strrchr (filename, '\\'))) if (!(fn = strrchr (filename, '/')) && !(fn = strrchr (filename, '\\')))
fn = filename; fn = filename;
else else
@ -3915,7 +3917,8 @@ static void ansi_make_HDR1 (HDR1 *hdr1, VOL1 *vol, HDR4 *hdr4, const char *filen
fn = fn_cpy; fn = fn_cpy;
ext = strrchr (fn_cpy, '.'); ext = strrchr (fn_cpy, '.');
if (ext) { if (ext) {
while ((c = strchr (fn_cpy, '.')) != ext) while (((c = strchr (fn_cpy, '.')) != NULL) &&
(c != ext))
*c = '_'; /* translate extra .'s to _ */ *c = '_'; /* translate extra .'s to _ */
} }
memset (hdr1, ' ', sizeof (*hdr1)); memset (hdr1, ' ', sizeof (*hdr1));
@ -3970,6 +3973,8 @@ static void ansi_fill_text_buffer (FILE *f, char *buf, size_t buf_size, size_t r
char rec_size_str[16]; char rec_size_str[16];
start = ftell (f); start = ftell (f);
if (start < 0)
break;
if (!fgets (tmp, buf_size, f)) if (!fgets (tmp, buf_size, f))
break; break;
rec_size = strlen (tmp); rec_size = strlen (tmp);