From 678e57098e8a2377cb008db7358de529fb9fe3e4 Mon Sep 17 00:00:00 2001
From: Kevin Squire <kevin.squire@gmail.com>
Date: Tue, 5 Mar 2013 19:45:50 -0800
Subject: [PATCH 1/2] Fix findnext on BitArrays

---
 base/bitarray.jl | 22 ++++++++++++++++++++--
 test/bitarray.jl | 14 ++++++++++++++
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/base/bitarray.jl b/base/bitarray.jl
index d0d33b17b921d..5ffbf355eb4dc 100644
--- a/base/bitarray.jl
+++ b/base/bitarray.jl
@@ -1477,7 +1477,16 @@ end
 # returns the index of the next non-zero element, or 0 if all zeros
 function findnext(B::BitArray, start::Integer)
     Bc = B.chunks
-    for i = div(start-1,64)+1:length(Bc)
+
+    chunk_start = div(start-1, 64)+1
+    within_chunk_start = start-1-chunk_start*64
+    mask = _msk64-((1<<within_chunk_start)-1)
+
+    if Bc[chunk_start] & mask != 0
+        return (chunk_start-1) << 6 + trailing_zeros(Bc[chunk_start] & mask) + 1
+    end
+
+    for i = chunk_start+1:length(Bc)
         if Bc[i] != 0
             return (i-1) << 6 + trailing_zeros(Bc[i]) + 1
         end
@@ -1493,7 +1502,16 @@ function findnextnot(B::BitArray, start::Integer)
     if l == 0
         return 0
     end
-    for i = div(start-1,64)+1:l-1
+
+    chunk_start = div(start-1, 64)+1
+    within_chunk_start = start-1-chunk_start*64
+    mask = (1<<within_chunk_start)-1
+
+    if Bc[chunk_start] | mask != _msk64
+        return (chunk_start-1) << 6 + trailing_ones(Bc[chunk_start] | mask) + 1
+    end
+
+    for i = chunk_start+1:l-1
         if Bc[i] != _msk64
             return (i-1) << 6 + trailing_ones(Bc[i]) + 1
         end
diff --git a/test/bitarray.jl b/test/bitarray.jl
index bf0c2dd32e14d..a4bfcd94a1a98 100644
--- a/test/bitarray.jl
+++ b/test/bitarray.jl
@@ -517,6 +517,20 @@ b1 = randbool(v1)
 
 @check_bit_operation find Vector{Int} (b1,)
 
+b1 = trues(v1)
+for i = 0:v1-1
+    @test findfirst(b1 >> i) == i+1
+    @test Base.findfirstnot(~(b1 >> i)) == i+1
+end
+
+for i = 3:v1-1
+    for j = 2:i
+        submask = b1 << (v1-j+1)
+        @test findnext((b1 >> i) | submask,j) == i+1
+        @test Base.findnextnot((~(b1 >> i)) $ submask,j) == i+1
+    end
+end
+
 b1 = randbool(n1, n2)
 @check_bit_operation findn_nzs (Vector{Int}, Vector{Int}, BitArray) (b1,)
 

From 86df5a6529053b73db875ab2dace8699a504e25f Mon Sep 17 00:00:00 2001
From: Kevin Squire <kevin.squire@gmail.com>
Date: Wed, 6 Mar 2013 00:10:31 -0800
Subject: [PATCH 2/2] Update findnext to use helper macros.

---
 base/bitarray.jl | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/base/bitarray.jl b/base/bitarray.jl
index 5ffbf355eb4dc..129cb67cca2be 100644
--- a/base/bitarray.jl
+++ b/base/bitarray.jl
@@ -1478,9 +1478,9 @@ end
 function findnext(B::BitArray, start::Integer)
     Bc = B.chunks
 
-    chunk_start = div(start-1, 64)+1
-    within_chunk_start = start-1-chunk_start*64
-    mask = _msk64-((1<<within_chunk_start)-1)
+    chunk_start = @_div64(start-1)+1
+    within_chunk_start = @_mod64(start-1)
+    mask = _msk64 << within_chunk_start
 
     if Bc[chunk_start] & mask != 0
         return (chunk_start-1) << 6 + trailing_zeros(Bc[chunk_start] & mask) + 1
@@ -1503,9 +1503,9 @@ function findnextnot(B::BitArray, start::Integer)
         return 0
     end
 
-    chunk_start = div(start-1, 64)+1
-    within_chunk_start = start-1-chunk_start*64
-    mask = (1<<within_chunk_start)-1
+    chunk_start = @_div64(start-1)+1
+    within_chunk_start = @_mod64(start-1)
+    mask = ~(_msk64 << within_chunk_start)
 
     if Bc[chunk_start] | mask != _msk64
         return (chunk_start-1) << 6 + trailing_ones(Bc[chunk_start] | mask) + 1