Hi all:
I have this source line in my modified or1200 test suite:
// Subtract a large negative from a large positive number. Should set
// both the overflow and carry flags.
TEST_INST_FF_I32_I32 0, SPR_SR_CY | SPR_SR_OV, l.sub, 0x7fffffff,
0x80000000
which translates into the following pseudo-instructions:
set carry flag
set overflow flag
l.sub 0x7fffffff, 0x80000000
When run against or1ksim, it generates the following results:
0xffffffff, carry flag set, overflow flag set
However, it looks different when run against ORPSoC V2's or1200 RTL
model (simulated with Icarus Verilog):
0xffffffff, carry flag set, _NO_ overflow flag
I'm having similar issues with the multiply instructions, many carry and
overflow flags are different. I wonder if I've made a mistake somewhere.
Or are we really so lucky that nobody has ever noticed?
Thanks,
rdiez
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