This is an example of a simple P-warrior. A program that stores values in P-Space, that determines which strategy it will use.
The execution starts at res. Where the value -1 is loaded into the B-field. Execution continues to label ‘str’. The A-field of _STR is #0, and str1 is 5 addresses forward. Therefore the line for ‘str’ is ldp.a 0, 5. 0 in the P-Space is equal to -1, therefore ldp.a changes str1’s A-Field to -1.
Execution then continues to the if condition sne.ab #0 , res
This checks to see if both A and B fields are equivalent, if they are, execute the next instruction. If not, skip. Since res is equal to -1, they are not equal. Skipping the ‘lost’ label.
mod.a #2, str1
Does the operation -1 % 2 = 1
Making str1’s A-Field equal to 1
stp.ab str1, _STR stores the value of 1 into the 0 space in the P-Space.
Since str1’s A-Field is equal to 1. And _STR is 1, which points to str1. And since str1’s B-Field is equal to 2 (imp is two addresses forward), this stores 1 into the 2 P-field.
Now execution continues to the str1 label.
jmp @1 , 1
The @1 signifies that jmp’s B-field now points to dat 0, stream ‘s B-field. Which is equal to 2.
So str1 becomes:
jmp 1+(2) , 1
Execution jumps to the stream label. And since djn.f’s A-field is a direct/immediate value, it will continuously jump to itself.
Goes 11 addresses behind. Decrement the B value of that address, and then jump from the B value of that address.