W = value
addlw 255 - Hi ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw (Hi - Lo) + 1 mov Hack, W mov W, #(Hi - Lo) + 1 add W, Hack
Carry is set if W is in range Lo - Hi
It works for all values of Hi and Lo although it is not optimal for 255 and 0. It even works for ranges that wrap around 255 back to 0. For instance, if you set Lo to 240 and Hi to 15, it will match 0..15 and also 240..255. And it works for signed numbers. You can set Lo to -3 and Hi to 5 to match -3..+5.
The only requirement is that your assembler must truncate literals to eight bits. If not, you can still use it by masking the literals yourself: ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;
addlw (255 - Hi) & 0ffhmov Hack, W mov W, #(255 - Hi) & ; 0ffh add W, Hack ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ; addlw ((Hi - Lo) + 1) & 0ffh mov Hack, W mov W, #((Hi - Lo) + 1) & ; 0ffh add W, HackFor example:
Lower = 50 Upper = 60 ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 255 - Hi equates to addlw 195 mov Hack, W mov W, #255 - Hi equates to addlw 195 add W, Hack ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw (Hi - Lo) + 1 equates to addlw 11 mov Hack, W mov W, #(Hi - Lo) + 1 equates to addlw 11 add W, Hack W = 50 ; lower limit ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 195 ; w = 245 mov Hack, W mov W, #195 ; w = 245 add W, Hack ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 11 ; w = 0, C = 1, result = OK mov Hack, W mov W, #11 ; w = 0, C = 1, result = OK add W, Hack W = 55 ; in range ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 195 ; w = 250 mov Hack, W mov W, #195 ; w = 250 add W, Hack ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 11 ; w = 5, C = 1, result = OK mov Hack, W mov W, #11 ; w = 5, C = 1, result = OK add W, Hack W = 60 ; upper limit ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 195 ; w = 255 mov Hack, W mov W, #195 ; w = 255 add W, Hack ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 11 ; w = 11, C = 1, result = OK mov Hack, W mov W, #11 ; w = 11, C = 1, result = OK add W, Hack W = 49 ; under minimum ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 195 ; w = 244 mov Hack, W mov W, #195 ; w = 244 add W, Hack ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 11 ; w = 255, C = 0, result = Not OK mov Hack, W mov W, #11 ; w = 255, C = 0, result = Not OK add W, Hack W = 61 ; over maximum ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 195 ; w = 0 mov Hack, W mov W, #195 ; w = 0 add W, Hack ;*** WARNING: ADDLW was expanded in three instructions! Check if previous instruction is a skip instruction. ;addlw 11 ; w = 11, C = 0, result = Not OK mov Hack, W mov W, #11 ; w = 11, C = 0, result = Not OK add W, Hack