REPTILE: EXAMPLE PROGRAMS

Reptile has a minimum instruction set which is capable of solving quite complicated problems.. In the coming lectures we will continue to add a few more instructions like PUSH, POP, CALL and RET but it is quite sufficient even without these instructions.. Below we will give examples of the sort of problems which are solvable by reptile

Note that these programs can be written in many different ways..

Summing all integers from 1 to N

The program has two variables, N and SUM. N is considered unsigned.
The program will sum all the integers between 1 and N
The program will write its result to the variable SUM.

In the following program, N is arbitrarily chosen as 60.

.data
           N: 60
           sum:  
.code 
           ldi 0 N 
           ld  0 0 
           jz out       //if N=0
loop       inc 1 
           add 2 2 1           
           dec 0 
           jz out 
           jmp loop 
out        ld 0 sum
           st 0 2
end        jmp end

Summing an alternating series

Same with the above, but this time evaluates 1-2+3-4+5-6+7-8+.... up to N.

.data
           N: 60
           sum:  
.code 
           ldi 0 N 
           ld  0 0 
           jz out       //if N=0
loop       inc 1 
           add 2 2 1           
           dec 0 
           jz out 
           inc 1
           sub 2 2 1
           dec 0
           jz out
           jmp loop 
out        ld 0 sum
           st 0 2
end        jmp end

Multiplying unsigned integers A and B

.data
           A:20
           B:30           
           mult:  
.code 
           ldi 0 A 
           ld  0 0 
           ldi 1 B
           ld 1 1
           jz out     //if B==0       
loop       add 2 2 0   
           dec 1           
           jz out
           jmp loop
           ld 0 mult
           st 0 2
end        jmp end

Reptile: Example Programs