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40 lines
1.6 KiB
Plaintext
40 lines
1.6 KiB
Plaintext
Comments:
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R1 holds n, for calculating the nth Fibonacci number
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R2 holds the number 1, for comparing <=1
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R3 will hold the answers, the nth Fibonacci number (and any intermediate results)
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R4
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R5
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(0x0) LDA R1 ##MEMORY_LOCATION_OF_n## (loads n into R1)
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(0x1) LDA R2 ##MEMORY_LOCATION_CONTAINING_0x1## (loads number 1 into R2)
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(0x2) LDA R3 ##MEMORY_LOCATION_OF_0x## (loads 0 into R3, we set 0 as the initial result)
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(0x3) LDA R4 ##MEMORY_LOCATION_OF_n## (loads n into R4)
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(0x4) LDA R6 ##MEMORY_LOCATION_CONTAINING_0xA## (loads 0xB, memory location of program end to R6)
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(0x5) LDA R7 ##MEMORY_LOCATION_CONTAINING_0x6## (loads 0x6, memory location for jumping back)
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(0x6) JC4 R6 R4 (if R4, in this case, n, is equal to 0, then jump to end, STP)
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(0x7) MLA R1 R2 R3 (multiply and add, same as in the source code y=y*a+b)
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(0x8) ADD R5 R5 R1 (adds y to the sum, so that sum+=y, as in the source code)
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(0x9) SBO R4 R4 (decrease R4, i.e. n by one, so no infinite loops occur)
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(0xA) JMP R7 (jumps back to check whether n>0 and if so, repeats again)
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(0xB) STP
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MOV
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JC6 ... R1 R2
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PSH R2
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Example that can be used with the instruction generator program:
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Requires setting the following data memory location:
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Set location '0' to value of n;
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Set location '1' to value of 1 (decimal number);
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Set location '2' to value of 0 (decimal number)
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