implement most bit-* on integers

heyLu · heyLu · commit 21640992a171 · 2014-11-05T19:30:52.000+01:00
unsigned-bit-shift-right is missing, but the others are there.
diff --git a/pixie/vm/bits.py b/pixie/vm/bits.py
@@ -0,0 +1,77 @@
+from pixie.vm.code import as_var
+from pixie.vm.object import affirm
+
+from pixie.vm.numbers import Integer
+
+import pixie.vm.rt as rt
+
+@as_var("bit-clear")
+def bit_clear(x, n):
+    affirm(isinstance(x, Integer) and isinstance(n, Integer), u"x and n must be Integers")
+    return rt.wrap(x.int_val() & ~(1 << n.int_val()))
+
+@as_var("bit-set")
+def bit_set(x, n):
+    affirm(isinstance(x, Integer) and isinstance(n, Integer), u"x and n must be Integers")
+    return rt.wrap(x.int_val() | (1 << n.int_val()))
+
+@as_var("bit-flip")
+def bit_flip(x, n):
+    affirm(isinstance(x, Integer) and isinstance(n, Integer), u"x and n must be Integers")
+    return rt.wrap(x.int_val() ^ (1 << n.int_val()))
+
+@as_var("bit-test")
+def bit_test(x, n):
+    affirm(isinstance(x, Integer) and isinstance(n, Integer), u"x and n must be Integers")
+    return rt.wrap((x.int_val() & (1 << n.int_val())) != 0)
+
+@as_var("bit-and")
+def bit_and(x, y):
+    affirm(isinstance(x, Integer) and isinstance(y, Integer), u"x and y must be Integers")
+    return rt.wrap(x.int_val() & y.int_val())
+
+@as_var("bit-or")
+def bit_or(x, y):
+    affirm(isinstance(x, Integer) and isinstance(y, Integer), u"x and y must be Integers")
+    return rt.wrap(x.int_val() | y.int_val())
+
+@as_var("bit-xor")
+def bit_xor(x, y):
+    affirm(isinstance(x, Integer) and isinstance(y, Integer), u"x and y must be Integers")
+    return rt.wrap(x.int_val() ^ y.int_val())
+
+@as_var("bit-shift-left")
+def bit_shift_left(x, n):
+    affirm(isinstance(x, Integer) and isinstance(n, Integer), u"x and n must be Integers")
+    return rt.wrap(x.int_val() << n.int_val())
+
+@as_var("bit-shift-right")
+def bit_shift_right(x, n):
+    affirm(isinstance(x, Integer) and isinstance(n, Integer), u"x and n must be Integers")
+    return rt.wrap(x.int_val() >> n.int_val())
+
+# unsigned-bit-shift-right (sets sign bit to zero)
+
+digits = "0123456789abcdefghijklmnopqrstuvwxyz"
+
+@as_var("bit-str")
+def bit_str(x, shift):
+    affirm(isinstance(x, Integer) and isinstance(shift, Integer), u"x and shift must be Integers")
+    x = x.int_val()
+    shift = shift.int_val()
+
+    buf = ['_'] * 32
+    char_pos = 32
+    radix = 1 << shift
+    mask = radix - 1
+    while True:
+        char_pos -= 1
+        buf[char_pos] = digits[x & mask]
+        x = x >> shift
+        if x == 0:
+            break
+
+    res = ""
+    for i in range(char_pos, char_pos + 32 - char_pos):
+        res += buf[i]
+    return rt.wrap(res)
diff --git a/pixie/vm/rt.py b/pixie/vm/rt.py
@@ -48,6 +48,7 @@ def wrapper(*args):
     sys.setrecursionlimit(10000) # Yeah we blow the stack sometimes, we promise it's not a bug
 
     import pixie.vm.numbers as numbers
+    import pixie.vm.bits as bits
     from pixie.vm.code import wrap_fn
     import pixie.vm.interpreter
     import pixie.vm.stacklet as stacklet
