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76876dd7bf
* doc/body.texi: Change documentation to no longer say it is a variant of the Fibonacci sequence, and document a proper implementation. Thanks to Jon Arintok for pointing out that the Fibonacci sequence generation was incorrect. It was documented, but still confusing. * check/fib.tst, check/fib.ok, check/bp.tst, check/bp.ok, doc/ifib.c, doc/rbif.c: Implement a proper Fibonacci sequence implementation.
53 lines
1.7 KiB
C
53 lines
1.7 KiB
C
#include <stdio.h>
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#include <lightning.h>
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static jit_state_t *_jit;
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typedef int (*pifi)(int); /* Pointer to Int Function of Int */
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int main(int argc, char *argv[])
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{
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pifi fib;
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jit_node_t *label;
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jit_node_t *call;
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jit_node_t *in; /* offset of the argument */
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jit_node_t *ref; /* to patch the forward reference */
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jit_node_t *zero; /* to patch the forward reference */
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init_jit(argv[0]);
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_jit = jit_new_state();
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label = jit_label();
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jit_prolog ();
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in = jit_arg ();
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jit_getarg (JIT_R0, in); /* R0 = n */
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zero = jit_beqi (JIT_R0, 0);
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jit_movr (JIT_V0, JIT_R0); /* V0 = R0 */
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jit_movi (JIT_R0, 1);
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ref = jit_blei (JIT_V0, 2);
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jit_subi (JIT_V1, JIT_V0, 1); /* V1 = n-1 */
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jit_subi (JIT_V2, JIT_V0, 2); /* V2 = n-2 */
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jit_prepare();
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jit_pushargr(JIT_V1);
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call = jit_finishi(NULL);
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jit_patch_at(call, label);
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jit_retval(JIT_V1); /* V1 = fib(n-1) */
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jit_prepare();
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jit_pushargr(JIT_V2);
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call = jit_finishi(NULL);
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jit_patch_at(call, label);
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jit_retval(JIT_R0); /* R0 = fib(n-2) */
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jit_addr(JIT_R0, JIT_R0, JIT_V1); /* R0 = R0 + V1 */
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jit_patch(ref); /* patch jump */
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jit_patch(zero); /* patch jump */
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jit_retr(JIT_R0);
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/* call the generated code, passing 32 as an argument */
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fib = jit_emit();
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jit_clear_state();
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printf("fib(%d) = %d\n", 32, fib(32));
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jit_destroy_state();
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finish_jit();
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return 0;
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}
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