ABSTC ACC
6-20
ABSTC ACC Absolute Value of Accumulator and Load TC
SYNTAX OPTIONS OPCODE OBJMODE RPT CYC
ABSTC ACC 0101 0110 0101 1111 1 − 1
Operands ACC Accumulator register
Description Replace the content of the ACC register with its absolute value and load the
test control (TC) bit with the sign bit XORed with the previous value of the
test control bit:
if(ACC = 0x8000 0000)
{
If (OVM = 1)
ACC = 0x7FFF FFFF;
else
ACC = 0x8000 0000;
V = 1;
TC = TC XOR 1;
{
else
{
if(ACC < 0)
ACC = −ACC;
TC = TC XOR 1;
}
C = 0;
Flags and
N After the operation, the N flag is set if bit 31 of the ACC is 1, else N is cleared.
Modes
Z After the operation, the Z flag is set if the ACC is zero, else Z is cleared.
C The C flag bit is cleared.
V If (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 If (ACC < 0) at the start of the operation, then TC = TC XOR 1; otherwise, TC
is not affected.
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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