Intel Microcontroller, 80C196NU manual Table C-4. Effect of SME and FME Bit Combinations, Sme Fme

Models: Microcontroller 80C196NU 8XC196NP

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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.

 

 

 

C-7

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Intel Microcontroller, 80C196NU, 8XC196NP manual Table C-4. Effect of SME and FME Bit Combinations, Sme Fme