ADD W,fr | |
| Description: | Add fr into W |
| Operation: | W += fr |
| Flags affected: | C DC Z |
| Registers affected: | W |
| Sources referenced: | fr |
| Cycles: | 1 |
| Opcode: | |
| Details: | SX Users Manual page # 70 |
| Microchip PIC syntax: | ADDWF fr,0 |
| Notes: | |
Add fr to W
Operation: W =W + fr
Flags affected: C, DC, Z
Opcode: 0001 110f ffff
Description: 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.
Config. Option: 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.