diff --git a/basis/math/bitwise/bitwise-docs.factor b/basis/math/bitwise/bitwise-docs.factor
index 247523369b..4f2606bda0 100644
--- a/basis/math/bitwise/bitwise-docs.factor
+++ b/basis/math/bitwise/bitwise-docs.factor
@@ -1,12 +1,8 @@
-USING: help.markup help.syntax math ;
+! Copyright (C) 2008 Doug Coleman.
+! See http://factorcode.org/license.txt for BSD license.
+USING: help.markup help.syntax math sequences ;
 IN: math.bitwise
 
-ARTICLE: "math-bitfields" "Constructing bit fields"
-"Some applications, such as binary communication protocols and assemblers, need to construct integers from elaborate bit field specifications. Hand-coding this using " { $link shift } " and " { $link bitor } " results in repetitive code. A higher-level facility exists to factor out this repetition:"
-{ $subsection bitfield } ;
-
-ABOUT: "math-bitfields"
-
 HELP: bitfield
 { $values { "values..." "a series of objects" } { "bitspec" "an array" } { "n" integer } }
 { $description "Constructs an integer from a series of values on the stack together with a bit field specifier, which is an array whose elements have one of the following shapes:"
@@ -42,9 +38,307 @@ HELP: bits
 { $example "USING: math.bitwise prettyprint ;" "HEX: 123abcdef 16 bits .h" "cdef" } ;
 
 HELP: bitroll
-{ $values { "x" "an integer (input)" } { "s" "an integer (shift)" } { "w" "an integer (wrap)" } { "y" integer } }
+{ $values { "x" integer } { "s" "a shift integer" } { "w" "a wrap integer" } { "y" integer }
+}
 { $description "Roll n by s bits to the left, wrapping around after w bits." }
 { $examples
     { $example "USING: math.bitwise prettyprint ;" "1 -1 32 bitroll .b" "10000000000000000000000000000000" }
     { $example "USING: math.bitwise prettyprint ;" "HEX: ffff0000 8 32 bitroll .h" "ff0000ff" }
 } ;
+
+HELP: bit-clear?
+{ $values
+     { "x" integer } { "n" integer }
+     { "?" "a boolean" }
+}
+{ $description "Returns " { $link t } " if the nth bit is set to zero." }
+{ $examples 
+    { $example "USING: math.bitwise prettyprint ;"
+               "HEX: ff 8 bit-clear? ."
+               "t"
+    }
+    { $example "" "USING: math.bitwise prettyprint ;"
+               "HEX: ff 7 bit-clear? ."
+               "f"
+    }
+} ;
+
+{ bit? bit-clear? set-bit clear-bit } related-words
+
+HELP: bit-count
+{ $values
+     { "x" integer }
+     { "n" integer }
+}
+{ $description "Returns the number of set bits as an integer." }
+{ $examples 
+    { $example "USING: math.bitwise prettyprint ;"
+               "HEX: f0 bit-count ."
+               "4"
+    }
+    { $example "USING: math.bitwise prettyprint ;"
+               "-7 bit-count ."
+               "2"
+    }
+} ;
+
+HELP: bitroll-32
+{ $values
+     { "n" integer } { "s" integer }
+     { "n'" integer }
+}     
+{ $description "Rolls the number " { $snippet "n" } " by " { $snippet "s" } " bits to the left, wrapping around after 32 bits." }
+{ $examples 
+    { $example "USING: math.bitwise prettyprint ;"
+               "HEX: 1 10 bitroll-32 .h"
+               "400"
+    }
+    { $example "USING: math.bitwise prettyprint ;"
+               "HEX: 1 -10 bitroll-32 .h"
+               "400000"
+    }
+} ;
+
+HELP: bitroll-64
+{ $values
+     { "n" integer } { "s" "a shift integer" }
+     { "n'" integer }
+}
+{ $description "Rolls the number " { $snippet "n" } " by " { $snippet "s" } " bits to the left, wrapping around after 64 bits." }
+{ $examples 
+    { $example "USING: math.bitwise prettyprint ;"
+               "HEX: 1 10 bitroll-64 .h"
+               "400"
+    }
+    { $example "USING: math.bitwise prettyprint ;"
+               "HEX: 1 -10 bitroll-64 .h"
+               "40000000000000"
+    }
+} ;
+
+{ bitroll bitroll-32 bitroll-64 } related-words
+
+HELP: clear-bit
+{ $values
+     { "x" integer } { "n" integer }
+     { "y" integer }
+}
+{ $description "Sets the nth bit of " { $snippet "x" } " to zero." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "HEX: ff 7 clear-bit .h"
+        "7f"
+    }
+} ;
+
+HELP: flags
+{ $values
+     { "values" sequence }
+}
+{ $description "Constructs a constant flag value from a sequence of integers or words that output integers. The resulting constant is computed at compile-time, which makes this word as efficient as using a literal integer." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "IN: scratchpad"
+        ": MY-CONSTANT HEX: 1 ; inline"
+        "{ HEX: 20 MY-CONSTANT BIN: 100 } flags .h"
+        "25"
+    }
+} ;
+
+HELP: mask
+{ $values
+     { "x" integer } { "n" integer }
+     { "?" "a boolean" }
+}
+{ $description "After the operation, only the bits that were set in both the mask and the original number are set." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "BIN: 11111111 BIN: 101 mask .b"
+        "101"
+    }
+} ;
+
+HELP: mask-bit
+{ $values
+     { "m" integer } { "n" integer }
+     { "m'" integer }
+}
+{ $description "Turns off all bits besides the nth bit." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "HEX: ff 2 mask-bit .b"
+        "100"
+    }
+} ;
+
+HELP: mask?
+{ $values
+     { "x" integer } { "n" integer }
+     { "?" "a boolean" }
+}
+{ $description "Returns true if all of the bits in the mask " { $snippet "n" } " are set in the integer input " { $snippet "x" } "." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "HEX: ff HEX: f mask? ."
+        "t"
+    }
+
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "HEX: f0 HEX: 1 mask? ."
+        "f"
+    }
+} ;
+
+HELP: on-bits
+{ $values
+     { "n" integer }
+     { "m" integer }
+}
+{ $description "Returns an integer with " { $snippet "n" } " bits set." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "6 on-bits .h"
+        "3f"
+    }
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "64 on-bits .h"
+        "ffffffffffffffff"
+    }
+}
+;
+
+HELP: set-bit
+{ $values
+     { "x" integer } { "n" integer }
+     { "y" integer }
+}
+{ $description "Sets the nth bit of " { $snippet "x" } "." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "0 5 set-bit .h"
+        "20"
+    }
+} ;
+
+HELP: shift-mod
+{ $values
+     { "n" integer } { "s" integer } { "w" integer }
+     { "n" integer }
+}
+{ $description "" } ;
+
+HELP: unmask
+{ $values
+     { "x" integer } { "n" integer }
+     { "?" "a boolean" }
+}
+{ $description "Clears the bits in " { $snippet "x" } " if they are set in the mask " { $snippet "n" } "." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "HEX: ff  HEX: 0f unmask .h"
+        "f0"
+    }
+} ;
+
+HELP: unmask?
+{ $values
+     { "x" integer } { "n" integer }
+     { "?" "a boolean" }
+}
+{ $description "Tests whether unmasking the bits in " { $snippet "x" } " would return an integer greater than zero." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "HEX: ff  HEX: 0f unmask? ."
+        "t"
+    }
+} ;
+
+HELP: w*
+{ $values
+     { "int" integer } { "int" integer }
+     { "int" integer }
+}
+{ $description "Multiplies two integers and wraps the result to 32 bits." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "HEX: ffffffff HEX: 2 w* ."
+        "4294967294"
+    }
+} ;
+
+HELP: w+
+{ $values
+     { "int" integer } { "int" integer }
+     { "int" integer }
+}
+{ $description "Adds two integers and wraps the result to 32 bits." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "HEX: ffffffff HEX: 2 w+ ."
+        "1"
+    }
+} ;
+
+HELP: w-
+{ $values
+     { "int" integer } { "int" integer }
+     { "int" integer }
+}
+{ $description "Subtracts two integers and wraps the result to 32 bits." }
+{ $examples
+    { $example "USING: math.bitwise kernel prettyprint ;"
+        "HEX: 0 HEX: ff w- ."
+        "4294967041"
+    }
+} ;
+
+HELP: wrap
+{ $values
+     { "m" integer } { "n" integer }
+     { "m'" integer }
+}
+{ $description "Wraps an integer " { $snippet "m" } " by modding it by " { $snippet "n" } ". This word is uses bitwise arithmetic and does not actually call the modulus word, and as such can only mod by powers of two." }
+{ $examples "Equivalent to modding by 8:"
+    { $example 
+        "USING: math.bitwise prettyprint ;"
+        "HEX: ffff 8 wrap .h"
+        "7"
+    }
+} ;
+
+ARTICLE: "math-bitfields" "Constructing bit fields"
+"Some applications, such as binary communication protocols and assemblers, need to construct integers from elaborate bit field specifications. Hand-coding this using " { $link shift } " and " { $link bitor } " results in repetitive code. A higher-level facility exists to factor out this repetition:"
+{ $subsection bitfield } ;
+
+ARTICLE: "math.bitwise" "Bitwise arithmetic"
+"The " { $vocab-link "math.bitwise" } " vocabulary can implements bitwise arithmetic words that are useful for efficiency, low-level programming, and interfacing with C libraries." $nl
+"Setting and clearing bits:"
+{ $subsection set-bit }
+{ $subsection clear-bit }
+"Testing if bits are set or clear:"
+{ $subsection bit? }
+{ $subsection bit-clear? }
+"Operations with bitmasks:"
+{ $subsection mask }
+{ $subsection unmask }
+{ $subsection mask? }
+{ $subsection unmask? }
+"Generating an integer with n set bits:"
+{ $subsection on-bits }
+"Counting the number of set bits:"
+{ $subsection bit-count }
+"More efficient modding by powers of two:"
+{ $subsection wrap }
+"Bit-rolling:"
+{ $subsection bitroll }
+{ $subsection bitroll-32 }
+{ $subsection bitroll-64 }
+"32-bit arithmetic:"
+{ $subsection w+ }
+{ $subsection w- }
+{ $subsection w* }
+"Bitfields:"
+{ $subsection flags }
+{ $subsection "math-bitfields" } ;
+
+ABOUT: "math.bitwise"
diff --git a/basis/math/bitwise/bitwise-tests.factor b/basis/math/bitwise/bitwise-tests.factor
index 8b13cb23b3..4422992956 100644
--- a/basis/math/bitwise/bitwise-tests.factor
+++ b/basis/math/bitwise/bitwise-tests.factor
@@ -27,3 +27,5 @@ IN: math.bitwise.tests
 [ 3 ] [ foo ] unit-test
 [ 3 ] [ { a b } flags ] unit-test
 \ foo must-infer
+
+[ 1 ] [ { 1 } flags ] unit-test
diff --git a/basis/math/bitwise/bitwise.factor b/basis/math/bitwise/bitwise.factor
index 871f40e74c..ad1907fcb0 100644
--- a/basis/math/bitwise/bitwise.factor
+++ b/basis/math/bitwise/bitwise.factor
@@ -1,4 +1,4 @@
-! Copyright (C) 2007, 2008 Slava Pestov.
+! Copyright (C) 2007, 2008 Slava Pestov, Doug Coleman.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: arrays kernel math math.functions sequences
 sequences.private words namespaces macros hints
@@ -8,28 +8,29 @@ IN: math.bitwise
 ! utilities
 : clear-bit ( x n -- y ) 2^ bitnot bitand ; inline
 : set-bit ( x n -- y ) 2^ bitor ; inline
-: bit-clear? ( x n -- ? ) 2^ bitand zero? ; inline
+: bit-clear? ( x n -- ? ) 2^ bitand 0 = ; inline
 : unmask ( x n -- ? ) bitnot bitand ; inline
 : unmask? ( x n -- ? ) unmask 0 > ; inline
 : mask ( x n -- ? ) bitand ; inline
 : mask? ( x n -- ? ) mask 0 > ; inline
 : wrap ( m n -- m' ) 1- bitand ; inline
 : bits ( m n -- m' ) 2^ wrap ; inline
-: mask-bit ( m n -- m' ) 1- 2^ mask ; inline
+: mask-bit ( m n -- m' ) 2^ mask ; inline
+: on-bits ( n -- m ) 2^ 1- ; inline
 
 : shift-mod ( n s w -- n )
-    >r shift r> 2^ wrap ; inline
+    [ shift ] dip 2^ wrap ; inline
 
 : bitroll ( x s w -- y )
-     [ wrap ] keep
-     [ shift-mod ]
-     [ [ - ] keep shift-mod ] 3bi bitor ; inline
+    [ wrap ] keep
+    [ shift-mod ]
+    [ [ - ] keep shift-mod ] 3bi bitor ; inline
 
-: bitroll-32 ( n s -- n' ) 32 bitroll ;
+: bitroll-32 ( n s -- n' ) 32 bitroll ; inline
 
 HINTS: bitroll-32 bignum fixnum ;
 
-: bitroll-64 ( n s -- n' ) 64 bitroll ;
+: bitroll-64 ( n s -- n' ) 64 bitroll ; inline
 
 HINTS: bitroll-64 bignum fixnum ;
 
@@ -40,7 +41,7 @@ HINTS: bitroll-64 bignum fixnum ;
 
 ! flags
 MACRO: flags ( values -- )
-    [ 0 ] [ [ execute bitor ] curry compose ] reduce ;
+    [ 0 ] [ [ dup word? [ execute ] when bitor ] curry compose ] reduce ;
 
 ! bitfield
 <PRIVATE
@@ -51,7 +52,7 @@ M: integer (bitfield-quot) ( spec -- quot )
     [ swapd shift bitor ] curry ;
 
 M: pair (bitfield-quot) ( spec -- quot )
-    first2 over word? [ >r swapd execute r> ] [ ] ?
+    first2 over word? [ [ swapd execute ] dip ] [ ] ?
     [ shift bitor ] append 2curry ;
 
 PRIVATE>
@@ -91,4 +92,4 @@ M: bignum (bit-count)
 PRIVATE>
 
 : bit-count ( x -- n )
-    dup 0 >= [ (bit-count) ] [ bitnot (bit-count) ] if ; inline
+    dup 0 < [ bitnot ] when (bit-count) ; inline