######### Internal Registers ###########
i0 - Holds 0 Constant
i1 - Holds 1 Constant
i2 - Free Register, use of "mov_imm2", which does opposite, moves reg into external
i3 - Holds Result of Cmp Operations AND mov_imm
######### Normal Registers ###########
r0
r1
r2
r3
r4
r5
r6
r7
Constraints
Rtype - usually stores in first operand (3 bit, so more operations)
- Try to use lower registers first (r0-r3)
Constraints/ Things to Check For good assembly
1. 2nd register # doesn't not exceed 3. ex) mov r4 r5 != RIGHT
2. If you ever have register-use problems, follow this rule:
- Have one lower register (r0-r3) for problems
- To use for something like "add r7, r5"
instead use "mov r5, r2; add r7 r2;"
Hammond Distance Sub Function
1. XOR two bytes
2. Begin Loop #1
See whole byte = 0, if so, exit and report
Else, Is LSB 1?
If so, increment
Shift Right
Dynamic Instruction Count = 8 // Depends on the situation, but is cleaner
Alternative Loop #2
See whole byte = 0, if so, exit and report
Else, Is MSB 1?
If so, increment
Shift Right
Sub A - 1
And A with (A-1)
Dynamic Instruction Count = 8 // Depends on the situation, but is cleaner
Algorithm:
Load First Byte from Array from Memory location @ 128
Begin OUTer Loop of Going through each array
Begin INNER Loop of Comparing current byte to each byte in array (N^2 runtime)
// Load first array with counter @ Address 128
// Have 2 ptrs, one for inner loop, and one for outer loop, r0 and r1
// i0 for Holding 0
// i1 for Holding 1
// i2 (Free Reg) HOLDS 288 Stores end number for iterations 128 + 160
// i3 for Compares & mov_imm values
// r0 for PTR #1
// r1 for PTR #2
// r2
// r3 for temp Hammon
// r4 for Hammo
// r5 for outer byte
// r6 for inner byte
// r7 , re-use // For PTR #1 reuse