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nickpascucci/indirect.s

Created March 31, 2021 08:23
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Porting Jonesforth to RISC-V
Raw
indirect.s
/* Test program to evaluate behavior of jalr for indirect threading.
See the comment in jonesforth.s starting after the NEXT macro on line 305.
Basic idea of the test: create an indirect threaded word manually, and use jalr
to jump into it to see what it does in the debugger.
*/
.text
_start:
la t1, _double /* Seed t1 by pointing to fake "double" word */
lw t0, 0(t1) /* Read address at _double to t0; this points to _dup now */
addi t1, t1, 4 /* Increment t1 by 4 to point to _plus */
lw t0, 0(t0) /* Read the codeword of _dup into t0; now _dup_body */
jalr x0, 0(t0) /* Jump to _dup_body */
_double:
/* .word _double_codeword - should be here, but we dont have an interpreter so skip */
.word _dup /* points to the codeword in _dup */
_dup:
.word _dup_body /* indirect threading codeword: where should we go now? */
_dup_body:
li x1, 8
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