Post by thread:Please help with math/logic operators!

Hello All, I'm trying to find commonly used math expressions in my PIC programming. How do the majority accomplish the following: if a>b call greater_than if ab call eq_or_gr if a=b AND c>d then call _and_ if a>b OR c>d then call _or_ What I'm using right now is a rather terse method of writing a single bit then refering to it to check for 'and'/'or'. Could someone please mail me some code explaining the above? Thanks in advance. Gerry

>I'm trying to find commonly used math expressions in my PIC >programming. How do the majority accomplish the following: I use the Parallax assembler, which has codes to do what you are after. (They don't have compare-and-call, but they do have compare-and-jump and compare-and-skip instructions. A compare-and-skip followed by a call works exactly backwards... but the result is what you want.) >if a>b call greater_than <-> CSA (compare and skip if above) >if a CSB (compare and skip if below) >if a=>b call eq_or_gr <-> CSAE (comp and skip if above or equal) >if a= CSBE (comp and skip if below or equal) >and also: >if a>b AND c>d then call _and_ CJBE A,B,SKIPME CJBE C,D,SKIPME CALL _and_ SKIPME [...] >if a>b OR c>d then call _or_ CJBE A,B,CALLIT CJBE C,D,CALLIT JMP SKIPIT CALLIT CALL _or_ SKIPIT [...] Note: I haven't tried compiling the above fragments, but they "should" work. If you don't use the Parallax assembler, you can convert the extended instructions directly into Microchip instructions. (The compare and jump instructions translate into four words; the compare and skip translate into three.) Grab a copy of the Parallax documentation from their ftp site, and print out the chip instruction section.

Gerry Smith <spam_OUTLIUKBTakeThisOuTKIRK.NORTHERNC.ON.CA> wrote: >I'm trying to find commonly used math expressions in my PIC >programming. How do the majority accomplish the following: Gerry: I have no idea how "the majority" do it (although I suspect that most of them do it badly)... Here's how I would do it: >if a>b call greater_than MOVF A,W SUBWF B,W SKPC CALL GREATER_THAN >if aif a=>b call eq_or_gr MOVF B,W SUBWF A,W SKPNC CALL EQ_OR_GR >if a=if a>b AND c>d then call _and_ MOVF A,W SUBWF B,W SKPNC GOTO $+5 MOVF C,W SUBWF D,W SKPC CALL _AND_ >if a>b OR c>d then call _or_ MOVF A,W SUBWF B,W SKPC GOTO $+4 MOVF C,W SUBWF D,W SKPC CALL _OR_ As usual, I haven't tested or even assembled the code I'm posting. -Andy -- Andrew Warren - .....fastfwdKILLspam@spam@ix.netcom.com Fast Forward Engineering, Vista, California

* This message contains the file '16bitcmp.asm', which has been * uuencoded. If you are using Pegasus Mail, then you can use * the browser's eXtract function to lift the original contents * out to a file, otherwise you will have to extract the message * and uudecode it manually. end Attachment converted: wonderlandtwo:16bitcmp.asm (????/----) (00003B15)