Parse numbers as signed values.

lib/dbf/column/base.rb

@@ -76,7 +76,7 @@ def underscored_name
       def type_cast_methods # nodoc
         {
           'N' => :unpack_number,
-          'I' => :unpack_unsigned_long,
+          'I' => :unpack_signed_long,
           'F' => :unpack_float,
           'Y' => :unpack_currency,
           'D' => :decode_date,
@@ -111,11 +111,11 @@ def unpack_number(value) # nodoc
       end
 
       def unpack_currency(value) # nodoc
-        (unpack_unsigned_long(value) / 10_000.0).to_f
+        (unpack_signed_long(value) / 10_000.0).to_f
       end
 
-      def unpack_unsigned_long(value) # nodoc
-        value.unpack('V')[0]
+      def unpack_signed_long(value) # nodoc
+        value.unpack('l<')[0]
       end
 
       def unpack_float(value) # nodoc

spec/dbf/column_spec.rb

@@ -58,6 +58,13 @@
           expect(column.type_cast(value)).to be_a(Fixnum)
           expect(column.type_cast(value)).to eq 135
         end
+
+        it 'supports negative Fixnum' do
+          value = '-135'
+          column = DBF::Column::Dbase.new table, "ColumnName", "N", 3, 0
+          expect(column.type_cast(value)).to be_a(Fixnum)
+          expect(column.type_cast(value)).to eq -135
+        end
       end
 
       context 'and more than 0 decimals' do
@@ -67,6 +74,13 @@
           expect(column.type_cast(value)).to be_a(Float)
           expect(column.type_cast(value)).to eq 13.5
         end
+
+        it 'supports negative Float' do
+          value = '-13.5'
+          column = DBF::Column::Dbase.new table, "ColumnName", "N", 2, 1
+          expect(column.type_cast(value)).to be_a(Float)
+          expect(column.type_cast(value)).to eq -13.5
+        end
       end
     end
 
@@ -84,6 +98,13 @@
         expect(column.type_cast(value)).to be_a(Float)
         expect(column.type_cast(value)).to eq 135.0
       end
+
+      it 'supports negative Float' do
+        value = '-135'
+        column = DBF::Column::Dbase.new table, "ColumnName", "F", 3, 0
+        expect(column.type_cast(value)).to be_a(Float)
+        expect(column.type_cast(value)).to eq -135.0
+      end
     end
 
     context "with type B (binary)" do
@@ -99,6 +120,12 @@
           expect(column.type_cast("\xEC\x51\xB8\x1E\x85\x6B\x31\x40")).to be_a(Float)
           expect(column.type_cast("\xEC\x51\xB8\x1E\x85\x6B\x31\x40")).to eq 17.42
         end
+
+        it 'supports negative binary' do
+          column = DBF::Column::Dbase.new table, "ColumnName", "B", 1, 2
+          expect(column.type_cast("\x00\x00\x00\x00\x00\xC0\x65\xC0")).to be_a(Float)
+          expect(column.type_cast("\x00\x00\x00\x00\x00\xC0\x65\xC0")).to eq -174.0
+        end
       end
     end
 
@@ -116,6 +143,13 @@
         expect(column.type_cast(value)).to be_a(Fixnum)
         expect(column.type_cast(value)).to eq 96643
       end
+
+      it "supports negative Fixnum" do
+        value = "\x24\xE1\xFF\xFF\xFF\xFF\xFF\xFF"
+        column = DBF::Column::Dbase.new table, "ColumnName", "I", 3, 0
+        expect(column.type_cast(value)).to be_a(Fixnum)
+        expect(column.type_cast(value)).to eq -7900
+      end
     end
 
     context 'with type L (logical/boolean)' do
@@ -234,6 +268,11 @@
       expect(column.type_cast(" \xBF\x02\x00\x00\x00\x00\x00")).to eq 18.0
     end
 
+    it 'supports negative currency' do
+      expect(column.type_cast("\xFC\xF0\xF0\xFE\xFF\xFF\xFF\xFF")).to be_a(Float)
+      expect(column.type_cast("\xFC\xF0\xF0\xFE\xFF\xFF\xFF\xFF")).to eq -1776.41
+    end
+
     context 'and 0 length' do
       it 'returns nil' do
         column = DBF::Column::Dbase.new table, "ColumnName", "Y", 0, 0