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em.c: change MAXMB to DEFMB, remove MEMSIZE and MEMMASK

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It was confusing that MAXMB is the default memory size, so renamed it
to DEFMB.  MEMSIZE was not necessary (half of MAXMB) and MEMMASK was
used only in mapva to limit physcal addresses when segmentation was
not enabled.  However, this appears to be a bug, because it would
cause memory addresses larger than physical memory to wrap and succeed
rather than generate a missing memory check.
This commit is contained in:
Jim Wilcoxson 2020-04-16 15:09:14 +00:00
parent 0396eb0a5b
commit d0cb6629c1
1 changed files with 8 additions and 8 deletions
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16
em.c
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@ -576,9 +576,7 @@ static jmp_buf bootjmp; /* for longjumps to the fetch loop */
speed up system boots and diagnostics during emulator testing.
*/
#define MAXMB 32 /* must be a power of 2 */
#define MEMSIZE MAXMB/2*1024*1024
#define MEMMASK MEMSIZE-1
#define DEFMB 32 /* must be a power of 2 */
#define MEM physmem
static unsigned short *physmem = NULL; /* system's physical memory */
@ -1005,11 +1003,11 @@ static pa_t mapva(ea_t ea, ea_t rp, short intacc, unsigned short *access) {
pa = stlbp->ppa | (ea & 0x3FF);
TRACE(T_MAP," for ea %o/%o, iacc=%d, stlbix=%d, pa=%o loaded at #%u\n", ea>>16, ea&0xffff, intacc, stlbix, pa, stlbp->load_ic);
} else {
pa = ea & MEMMASK;
pa = ea;
}
if (pa < gv.memlimit)
return pa;
#ifdef DBG
#if 0
printf(" map: Memory address '%o (%o/%o) is out of range 0-'%o (%o/%o) at #%d!\n", pa, pa>>16, pa & 0xffff, gv.memlimit-1, (gv.memlimit-1)>>16, (gv.memlimit-1) & 0xffff, gv.instcount);
#endif
@ -4463,7 +4461,7 @@ int main (int argc, char **argv) {
bootfile[0] = 0;
gv.pmap32bits = 0;
gv.csoffset = 0;
gv.memlimit = MEMSIZE;
gv.memlimit = DEFMB;
tport = 0;
nport = 0;
@ -4540,7 +4538,7 @@ int main (int argc, char **argv) {
if (i+1 < argc && argv[i+1][0] != '-') {
sscanf(argv[++i],"%d", &templ);
if (1 <= templ && templ <= 512)
gv.memlimit = templ*1024/2*1024;
gv.memlimit = templ;
else
fatal("-mem arg range is 1 to 512 (megabytes)\n");
} else
@ -4694,7 +4692,9 @@ int main (int argc, char **argv) {
gv.stlb[i].seg = 0xFFFF; /* marker for invalid STLB entry */
for (i=0; i < IOTLBENTS; i++)
gv.iotlb[i].valid = 0;
physmem = malloc(gv.memlimit * sizeof(*physmem));
gv.memlimit *= 1024 * 1024; /* memory size in bytes */
physmem = malloc(gv.memlimit);
gv.memlimit /= sizeof(*physmem); /* max Prime word address */
if (physmem == NULL) {
perror("Error allocating Prime memory block");
fatal("Can't allocate Prime memory block");