Subleq: Difference between revisions
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Minor tweak to wording, be more specific about character set changes.
(→bash: lowercase non-env vars; take advantage of arithmetic contexts; use printf instead of echo) |
m (Minor tweak to wording, be more specific about character set changes.) |
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The program should load the initial contents of the emulated machine's memory, set the instruction pointer to the first address (which is defined to be address 0), and begin emulating the machine, which works as follows:
:# Let '''A''' be the value in the memory location identified by the instruction pointer; let '''B''' and '''C''' be the values stored in the next two consecutive addresses in memory.
:# Advance the instruction pointer three words,
:# If '''A''' is '''-1''' (negative unity), then a character is read from the machine's input and its numeric value stored in the address given by '''B'''. '''C''' is unused.
:# If '''B''' is '''-1''' (negative unity), then the number contained in the address given by '''A''' is interpreted as a character and written to the machine's output. '''C''' is unused.
:# Otherwise, both '''A''' and '''B''' are treated as addresses. The number contained in address '''A''' is subtracted from the number in address '''B'''
:# If the instruction pointer becomes negative, execution halts.
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For purposes of this task, show the output of your solution when fed the below "Hello, world!" program.
As written,
<pre>15 17 -1 17 -1 -1 16 1 -1 16 3 -1 15 15 0 0 -1 72 101 108 108 111 44 32 119 111 114 108 100 33 10 0</pre>
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<pre>start:
0f 11 ff subleq (zero), (message), -1
11 ff ff
10 01 ff subleq (neg1), (start+1), -1
10 03 ff subleq (neg1), (start+3), -1
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