We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.
After compiling a .C file with the SRC directive to produce an assembler output file I have difficulty understanding releative jumps in the .src file. e.g. the line JC $ + 5H LJMP ?C0007 INC R7 Would appear to mean that, when there is a carrythe PC is incremented, first by 2 to get past the jump instruction, and then by a further 5 bytes. However, when there is a carry, the code should just bypass the LJMP instruction and execute the INC R7 instruction (I have examined this code in detail). i.e. a function equivalent is JC label LJMP ?C0007 label: INC R7 The LJMP instruction is only 3 bytes big therefore the offset would jump past the INC R7 instruction (assuming I interpreted the $ +5H offset correctly). The executable works correctly so could anybody tell me where I am going wrong ??????????????? Thank you
The part you have wrong is that the $+5 means that the PC is incremented by 5 from the beginning of the JC instruction. This means that the 2 bytes of the JC + the 3 bytes of the LJMP would be skipped, giving the correct implementation.