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C-7
REGISTERS
ACC_STAT
Table C-4. Effect of SME and FME Bit Combinations
SME FME Description
0 0 Sets the OVF and STOVF flags if the sign bits of the accumulator and the addend (the
number to be added to the contents of the accumulator) are equal, but the sign bit of the
result is the opposite.
0 1 Shifts the addend (the number to be added to the contents of the accumulator) left by one
bit before adding it to the accumulator. Sets the OVF and STOVF flags if the sign bits of the
accumulator and the addend are equal, but the sign bit of the result is the opposite.
1 0 Accumulates a signed integer value up or down to saturation and sets the STSAT flag.
Positive saturation changes the accumulator value to 7FFFFFFFH; negative saturation
changes the accumulator value to 80000000H. Accumulation proceeds normally after
saturation, which means that the accumulator value can increase from a negative saturation
or decrease from a positive saturation.
1 1 Shifts the addend (the number to be added to the contents of the accumulator) left by one
bit before adding it to the accumulator. Accumulates a signed integer value up or down to
saturation and sets the STSAT flag. Positive saturation changes the accumulator value to
7FFFFFFFH; negative saturation changes the accumulator value to 80000000H. Accumu-
lation proceeds normally after saturation, which means that the accumulator value can
increase from a negative saturation or decrease from a positive saturation.