ADD fr,W | |
| Description: | Add W into fr |
| Operation: | fr += W |
| Flags affected: | C DC Z |
| Registers affected: | fr |
| Sources referenced: | W |
| Cycles: | 1 |
| Opcode: | |
| Details: | SX Users Manual page # 69 |
| Microchip PIC syntax: | ADDWF fr,1 |
| Notes: | |
ADD fr, W
Add W to fr
Operation: fr = fr + W
Flags affected: C, DC, Z
Opcode: 0001 111f ffff
Description: This instruction adds the contents of W to the contents of the specified file register and writes the 8- bit result into the same file register. W 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 the file register. 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 configuration register has been programmed to 0, this instruction also adds the C flag as a carry- in input:
fr = fr + W + C
Cycles: 1
Example: add $12, W
This example adds the contents of W to file register 12h. For example, if the file register contains 7Fh and W contains 02h, this instruction adds 02h to 7Fh and writes the result, 81h, into the file register; and clears the C and Z flags. It sets the DC flag because of the carry from bit 3 to bit 4.