1 files changed, 69 insertions, 0 deletions
diff --git a/lisc/test/collatz.ssa b/lisc/test/collatz.ssa
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+# a solution for N=1000 to
+# https://projecteuler.net/problem=14
+# we use a fast local array to
+# memoize small collatz numbers
+#
+# todo, insert sign extensions
+
+@start
+	%mem  =l alloc4 4000
+
+@loop
+	%n    =w phi @start 1, @newm %n9, @oldm %n9
+	%cmax =w phi @start 0, @newm %c,  @oldm %cmax
+
+	%fin  =w cslt %n, 1000
+	jnz %fin, @cloop, @end
+
+@cloop
+	%n0   =w phi @loop %n, @odd %n2, @even %n3
+	%c0   =w phi @loop 0,  @odd %c1, @even %c1
+
+	%is1  =w ceq %n0, 1
+	jnz %is1, @endcl, @iter0
+
+@iter0
+	%ism  =w cslt %n0, %n
+	jnz %ism, @getmemo, @iter1   # we have it in the table
+
+@iter1
+	%c1   =w add %c0, 1
+	%p    =w and %n0, 1
+	jnz %p, @odd, @even
+
+@odd
+	%nn   =w add %n0, %n0        # compute %n2 = 3 * %n0 + 1
+	%n1   =w add %n0, %nn
+	%n2   =w add %n1, 1
+	jmp @cloop
+
+@even
+	%n3   =w div %n0, 2          # %n3 = %n0 / 2
+	jmp @cloop
+
+@getmemo
+	%idx00 =l add %n0, %n0
+	%idx0  =l add %idx00, %idx00
+	%loc0  =l add %idx0, %mem
+	%cn0   =w load %loc0
+	%c2  =w add %c0, %cn0
+
+@endcl
+	%c     =w phi @getmemo %c2, @cloop %c0
+
+	%idx10 =l add %n, %n
+	%idx1  =l add %idx10, %idx10
+	%loc1  =l add %idx1, %mem
+	storew %c, %loc1             # memorize the result
+	%n9    =w add 1, %n
+	%big   =w csle %cmax, %c
+	jnz %big, @newm, @oldm
+
+@newm
+	jmp @loop
+@oldm
+	jmp @loop
+
+@end
+	storew %cmax, $a
+	ret