SX Embedded Controller Instruction

This instruction adds the contents of the specified file register to the contents of W and writes the 8- bit result into W. The file register is left unchanged. The register contents are treated as unsigned values.

If the result of addition exceeds FFh, the C flag is set and the lower eight bits of the result are written to W. Otherwise, the C flag is cleared.

If there is a carry from bit 3 to bit 4, the DC (digit carry) flag is set. Otherwise, the flag is cleared.

If the result of addition is 00h, the Z flag is set. Otherwise, the flag is cleared. An addition result of 100h is considered zero and therefore sets the Z flag.

Affected by the the CF_ bit in FUSEX (DEVICE CARRYX).: If the CF bit in the FUSEX register has been programmed to 0, this instruction also adds the C flag as a carry- in input: W = W + fr + C

Cycles: 1

Example: add W,$ 12

This example adds the contents of file register 12h to W. For example, if the file register contains 81h and W contains 82h, this instruction adds 81h to 82h and writes the lower eight bits of the result, 03h, into W. It sets the C flag because of the carry out of bit 7, and clears the DC flag because there is no carry from bit 3 to bit 4. The Z flag is cleared because the result is nonzero.

See also:

• /techref/scenix/inst/addfrw.htm SX Embedded Controller Instruction - ADD fr,W