summaryrefslogtreecommitdiff
path: root/testsuite/gna/perf02/sub_160.vhd
diff options
context:
space:
mode:
authorTristan Gingold2014-12-07 11:40:58 +0100
committerTristan Gingold2014-12-07 11:40:58 +0100
commit2f4337f027ec97dd93642ea2db70873e9192fb3b (patch)
treed8c63b4cef84e33bae4e7018ce7abc07e0e3bd3c /testsuite/gna/perf02/sub_160.vhd
parentabe17103c669922a7349a7b2238d440b24d29f30 (diff)
downloadghdl-2f4337f027ec97dd93642ea2db70873e9192fb3b.tar.gz
ghdl-2f4337f027ec97dd93642ea2db70873e9192fb3b.tar.bz2
ghdl-2f4337f027ec97dd93642ea2db70873e9192fb3b.zip
Add perf02 (performance issue).
Diffstat (limited to 'testsuite/gna/perf02/sub_160.vhd')
-rw-r--r--testsuite/gna/perf02/sub_160.vhd68
1 files changed, 68 insertions, 0 deletions
diff --git a/testsuite/gna/perf02/sub_160.vhd b/testsuite/gna/perf02/sub_160.vhd
new file mode 100644
index 0000000..abae3d2
--- /dev/null
+++ b/testsuite/gna/perf02/sub_160.vhd
@@ -0,0 +1,68 @@
+library ieee;
+use ieee.std_logic_1164.all;
+
+library ieee;
+use ieee.numeric_std.all;
+
+entity sub_160 is
+ port (
+ output : out std_logic_vector(63 downto 0);
+ lt : out std_logic;
+ le : out std_logic;
+ sign : in std_logic;
+ ge : out std_logic;
+ in_a : in std_logic_vector(63 downto 0);
+ in_b : in std_logic_vector(63 downto 0)
+ );
+end sub_160;
+
+architecture augh of sub_160 is
+
+ signal carry_inA : std_logic_vector(65 downto 0);
+ signal carry_inB : std_logic_vector(65 downto 0);
+ signal carry_res : std_logic_vector(65 downto 0);
+
+ -- Signals to generate the comparison outputs
+ signal msb_abr : std_logic_vector(2 downto 0);
+ signal tmp_sign : std_logic;
+ signal tmp_eq : std_logic;
+ signal tmp_le : std_logic;
+ signal tmp_ge : std_logic;
+
+begin
+
+ -- To handle the CI input, the operation is '0' - CI
+ -- If CI is not present, the operation is '0' - '0'
+ carry_inA <= '0' & in_a & '0';
+ carry_inB <= '0' & in_b & '0';
+ -- Compute the result
+ carry_res <= std_logic_vector(unsigned(carry_inA) - unsigned(carry_inB));
+
+ -- Set the outputs
+ output <= carry_res(64 downto 1);
+
+ -- Other comparison outputs
+
+ -- Temporary signals
+ msb_abr <= in_a(63) & in_b(63) & carry_res(64);
+ tmp_sign <= sign;
+ tmp_eq <= '1' when in_a = in_b else '0';
+
+ tmp_le <=
+ tmp_eq when msb_abr = "000" or msb_abr = "110" else
+ '1' when msb_abr = "001" else
+ '1' when tmp_sign = '0' and (msb_abr = "010" or msb_abr = "001" or msb_abr = "111") else
+ '1' when tmp_sign = '1' and (msb_abr = "100" or msb_abr = "101") else
+ '0';
+
+ tmp_ge <=
+ '1' when msb_abr = "000" or msb_abr = "110" else
+ '1' when tmp_sign = '0' and (msb_abr = "100" or msb_abr = "101") else
+ '1' when tmp_sign = '1' and (msb_abr = "010" or msb_abr = "011" or msb_abr = "111") else
+ '0';
+
+ ge <= tmp_ge;
+ lt <= not(tmp_ge);
+ le <= tmp_le;
+
+end architecture;