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Christian Urban <christian dot urban at kcl dot ac dot uk>
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// A Transpiler for the Brainf*** language to C
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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//===============================================
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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//
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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// Call with
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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//
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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// amm bfc0.sc <<bf_program.bf>>
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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//
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//
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// Note: An interesting exercise is to call
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// gcc with -O3 instead of -O0 (see invocation
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// below).
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// simple instructions
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def instr(c: Char) : String = c match {
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case '>' => "ptr++;"
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case '<' => "ptr--;"
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case '+' => "(*ptr)++;"
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case '-' => "(*ptr)--;"
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case '.' => "putchar(*ptr);"
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case ',' => "*ptr = getchar();"
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case '[' => "while(*ptr){"
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case ']' => "}"
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case _ => ""
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}
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def instrs(prog: String) : String =
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prog.toList.map(instr(_)).mkString
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// adding boilerplate
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def compile(prog: String) : String =
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s"""#include <string.h>
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#include <stdio.h>
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int field[30000];
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int *ptr = &field[15000];
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int main() {
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memset(field, '\\0', 30000);
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${instrs(prog)}
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return 0;}"""
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def compile_to_file(name: String, prog: String) =
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os.write.over(os.pwd / name, compile(prog))
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// running the c-compiler over the transpiled
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// BF program and running the resulting binary
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def compile_and_run(prog: String) = {
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val tn = "tmp"
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compile_to_file(s"${tn}.c", prog)
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os.proc("gcc", "-O0", "-o", tn, s"${tn}.c").call() // call gcc
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os.proc("./tmp").call(stdout = os.Inherit) // run binary
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}
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// Running Testcases
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//===================
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def time_needed[T](n: Int, code: => T) = {
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val start = System.nanoTime()
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for (i <- 0 until n) code
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val end = System.nanoTime()
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(end - start)/(n * 1.0e9)
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}
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//@doc(" the argument should be a BF program ")
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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@main
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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def main(fname: String) = {
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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val bf_str = os.read(os.pwd / fname)
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println(s"${time_needed(1, compile_and_run(bf_str))} secs")
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Christian Urban <christian dot urban at kcl dot ac dot uk>
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}
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