3.12. Breakpoints and watches

Breakpoints and watches changes nothing in the code. They add debug information to emulators/debuggers. Currently this means adding info to the vice symbol file or the DebugDump file (C64Debugger).

You can set breakpoints in your code with the .break directive: 

    // Example 1
    ldy #10
loop:
    .break         // This will put a breakpoint on 'inc $d020'
    inc $d020
    dey
    .break "if y<5" // This will add a string as argument for the breakpoint
    bne loop 


    // Example 2 
    lda #10
    .break     // Will place a breakpoint at the first nop in the macro
    MyMacro()  

.macro MyMacro() {
    nop
    nop
    nop
}

The .break directive puts a breakpoint on the current memory position. As seen in the second breakpoint, you can add an argument to a breakpoint. The syntax of this is dependant on the consumer. The above case (.break "if y<5") is written for VICE's conditional expressions. VICE will then break if the y register is below 5.

Watches are defined like this

.watch $d018           // Watches $d018
.watch xpos+1          // Watches the address xpos+1
.watch $d000,$d00f     // Watches the range $d000-$d00f
.watch xpos,xpos+10,"store"   // Watches a range with the additional parameter "store" 
.watch count,,"hex8"   // you can leave the second argument empty

First argument is the address. If second argument is given its the range between the two. Third argument is an optional text string with additional information. Consult your emulater/debugger manual for possible content of third argument.

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