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3b2: Fix overflow of mask bits in INSFW/EXTFW

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- An overflow bug was causing INSFW and EXTFW to fail
  on Windows hosts compiled with Microsoft Visual Studio.
  This commit fixes the issue and causes 3B2 diagnostics
  to pass under win32.
This commit is contained in:
Seth Morabito 2017-12-10 12:01:08 -08:00
parent 2292f2cf3e
commit 06e7851d83
1 changed files with 13 additions and 5 deletions
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18
3B2/3b2_cpu.c
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@ -1373,7 +1373,7 @@ t_stat sim_instr(void)
/* Used for field calculation */
uint32 width, offset;
t_uint64 mask;
uint32 mask;
operand *src1, *src2, *src3, *dst;
@ -1989,8 +1989,12 @@ t_stat sim_instr(void)
case EXTFB:
width = (cpu_read_op(src1) & 0x1f) + 1;
offset = cpu_read_op(src2) & 0x1f;
mask = (1ul << width) - 1;
mask = (mask << offset) & WORD_MASK;
if (width >= 32) {
mask = -1;
} else {
mask = (1ul << width) - 1;
}
mask = mask << offset;
if (width + offset > 32) {
mask |= (1ul << ((width + offset) - 32)) - 1;
@ -2016,7 +2020,11 @@ t_stat sim_instr(void)
case INSFB:
width = (cpu_read_op(src1) & 0x1f) + 1;
offset = cpu_read_op(src2) & 0x1f;
mask = ((1ul << width) - 1) & WORD_MASK;
if (width >= 32) {
mask = -1;
} else {
mask = (1ul << width) - 1;
}
a = cpu_read_op(src3) & mask; /* src */
b = cpu_read_op(dst); /* dst */
@ -2171,7 +2179,7 @@ t_stat sim_instr(void)
cpu_set_c_flag(0);
break;
case ROTW:
a = cpu_read_op(src1) & 31;
a = cpu_read_op(src1) & 0x1f;
b = (uint32) cpu_read_op(src2);
mask = (CHAR_BIT * sizeof(a) - 1);
d = (b >> a) | (b << ((~a + 1) & mask));