NEGTC ACC
6-248
NEGTC ACC If TC is Equivalent to 1, Negate ACC
SYNTAX OPTIONS OPCODE OBJMODE RPT CYC
NEGTC ACC 0101 0110 0011 0010 1 − 1
Operands ACC Accumulator register
Description Based on the state of the test control (TC) bit, conditionally replace the
content of the ACC register with its negative:
if( TC = 1 )
{
if(ACC = 0x8000 0000)
{
V = 1;
if(OVM = 1)
ACC = 0x7FFF FFFF;
else
ACC = 0x8000 0000
}
else
ACC = −ACC;
if(ACC = 0x0000 0000)
C = 1;
else
C = 0;
}
Flags and
Modes
N After the operation, the N flag is set if bit 31 of the ACC is 1, else N is cleared.
Z After the operation, the Z flag is set if the ACC is zero, else Z is cleared.
C If (TC = 1 AND ACC = 0) set C; if (TC = 1 AND ACC != 0) clear C; otherwise C
is not modified.
V If (TC = 1 AND ACC = 0x8000 0000) at the start of the operation, this is
considered an overflow value and V is set. Otherwise, V is not affected.
TC The state of the TC bit is used as a test condition for the operation.
OVM If at the start of the operation, ACC = 0x8000 0000, then this is considered an
overflow value and the ACC value after the operation depends on OVM. If
OVM is cleared and TC = 1, ACC will be filled with 0x8000 0000. If OVM is set
and TC = 1, ACC will be saturated to 0x7FFF FFFF.
Repeat This instruction is not repeatable. If this instruction follows the RPT
instruction, it resets the repeat counter (RPTC) and executes only once.
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