From af9fe3467c91b46c053bdc81fcef45044ef09578 Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Mon, 8 Aug 2022 17:06:46 +1000 Subject: [PATCH] xilinx_mult: Prepare for doing signed multiplication This rearranges the way that partial products are generated and summed so that the partial products that could be negative in a signed multiplier are now sign-extended. The inputs are still zero-extended, however. The overflow detection logic now only detects 64-bit overflow, since 32-bit multiplications are handled in a separate multiplier. Signed-off-by: Paul Mackerras --- xilinx-mult.vhdl | 275 +++++++++++++++++++++++++---------------------- 1 file changed, 144 insertions(+), 131 deletions(-) diff --git a/xilinx-mult.vhdl b/xilinx-mult.vhdl index 97259b4..608810e 100644 --- a/xilinx-mult.vhdl +++ b/xilinx-mult.vhdl @@ -19,22 +19,24 @@ end entity multiply; architecture behaviour of multiply is signal m00_p, m01_p, m02_p, m03_p : std_ulogic_vector(47 downto 0); - signal m00_pc : std_ulogic_vector(47 downto 0); + signal m00_pc, m02_pc : std_ulogic_vector(47 downto 0); signal m10_p, m11_p, m12_p, m13_p : std_ulogic_vector(47 downto 0); - signal m11_pc, m12_pc, m13_pc : std_ulogic_vector(47 downto 0); + signal m10_pc, m12_pc : std_ulogic_vector(47 downto 0); signal m20_p, m21_p, m22_p, m23_p : std_ulogic_vector(47 downto 0); + signal m20_pc, m22_pc : std_ulogic_vector(47 downto 0); + signal pp0, pp1 : std_ulogic_vector(127 downto 0); + signal pp23 : std_ulogic_vector(127 downto 0); + signal sumlo : std_ulogic_vector(8 downto 0); signal s0_pc, s1_pc : std_ulogic_vector(47 downto 0); + signal s0_carry, p0_carry : std_ulogic_vector(3 downto 0); signal product : std_ulogic_vector(127 downto 0); signal addend : std_ulogic_vector(127 downto 0); - signal s0_carry, p0_carry : std_ulogic_vector(3 downto 0); - signal p0_mask : std_ulogic_vector(47 downto 0); signal p0_pat, p0_patb : std_ulogic; signal p1_pat, p1_patb : std_ulogic; - signal req_32bit, r32_1 : std_ulogic; signal rnot_1 : std_ulogic; signal valid_1 : std_ulogic; - signal overflow, ovf_in : std_ulogic; + signal overflow : std_ulogic; begin addend <= m_in.addend; @@ -55,12 +57,12 @@ begin PREG => 1 ) port map ( - A => "0000000" & m_in.data1(22 downto 0), + A => 6x"0" & m_in.data1(23 downto 0), ACIN => (others => '0'), ALUMODE => "0000", B => '0' & m_in.data2(16 downto 0), BCIN => (others => '0'), - C => "00000000000000" & addend(33 downto 0), + C => 14x"0" & addend(33 downto 0), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -106,12 +108,14 @@ begin BREG => 0, CARRYINREG => 0, CARRYINSELREG => 0, + CREG => 0, INMODEREG => 0, + MREG => 1, OPMODEREG => 0, PREG => 0 ) port map ( - A => "0000000" & m_in.data1(22 downto 0), + A => 6x"0" & m_in.data1(23 downto 0), ACIN => (others => '0'), ALUMODE => "0000", B => '0' & m_in.data2(33 downto 17), @@ -126,7 +130,7 @@ begin CEALUMODE => '0', CEB1 => '0', CEB2 => '0', - CEC => '1', + CEC => '0', CECARRYIN => '0', CECTRL => '0', CED => '0', @@ -168,12 +172,12 @@ begin PREG => 1 ) port map ( - A => "0000000" & m_in.data1(22 downto 0), + A => 6x"0" & m_in.data1(23 downto 0), ACIN => (others => '0'), ALUMODE => "0000", B => '0' & m_in.data2(50 downto 34), BCIN => (others => '0'), - C => x"0000000" & "000" & addend(50 downto 34), + C => 24x"0" & addend(57 downto 34), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -197,6 +201,7 @@ begin OPMODE => "0110101", P => m02_p, PCIN => (others => '0'), + PCOUT => m02_pc, RSTA => '0', RSTALLCARRYIN => '0', RSTALUMODE => '0', @@ -220,17 +225,17 @@ begin CARRYINSELREG => 0, CREG => 0, INMODEREG => 0, - MREG => 0, + MREG => 1, OPMODEREG => 0, - PREG => 1 + PREG => 0 ) port map ( - A => "0000000" & m_in.data1(22 downto 0), + A => 6x"0" & m_in.data1(23 downto 0), ACIN => (others => '0'), ALUMODE => "0000", B => "00000" & m_in.data2(63 downto 51), BCIN => (others => '0'), - C => x"000000" & '0' & addend(73 downto 51), + C => (others => '0'), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -245,15 +250,15 @@ begin CECTRL => '0', CED => '0', CEINMODE => '0', - CEM => '0', - CEP => m_in.valid, + CEM => m_in.valid, + CEP => '0', CLK => clk, D => (others => '0'), INMODE => "00000", MULTSIGNIN => '0', - OPMODE => "0110101", + OPMODE => "1010101", P => m03_p, - PCIN => (others => '0'), + PCIN => m02_pc, RSTA => '0', RSTALLCARRYIN => '0', RSTALUMODE => '0', @@ -277,16 +282,17 @@ begin CARRYINSELREG => 0, CREG => 0, INMODEREG => 0, + MREG => 0, OPMODEREG => 0, - PREG => 0 + PREG => 1 ) port map ( - A => "0000000000000" & m_in.data1(39 downto 23), + A => 6x"0" & m_in.data1(47 downto 24), ACIN => (others => '0'), ALUMODE => "0000", B => '0' & m_in.data2(16 downto 0), BCIN => (others => '0'), - C => x"000" & "00" & m01_p(39 downto 6), + C => (others => '0'), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -301,15 +307,16 @@ begin CECTRL => '0', CED => '0', CEINMODE => '0', - CEM => m_in.valid, - CEP => '0', + CEM => '0', + CEP => m_in.valid, CLK => clk, D => (others => '0'), INMODE => "00000", MULTSIGNIN => '0', - OPMODE => "0110101", + OPMODE => "0000101", P => m10_p, PCIN => (others => '0'), + PCOUT => m10_pc, RSTA => '0', RSTALLCARRYIN => '0', RSTALUMODE => '0', @@ -333,16 +340,17 @@ begin CARRYINSELREG => 0, CREG => 0, INMODEREG => 0, + MREG => 1, OPMODEREG => 0, PREG => 0 ) port map ( - A => "0000000000000" & m_in.data1(39 downto 23), + A => 6x"0" & m_in.data1(47 downto 24), ACIN => (others => '0'), ALUMODE => "0000", B => '0' & m_in.data2(33 downto 17), BCIN => (others => '0'), - C => x"000" & "00" & m02_p(39 downto 6), + C => (others => '0'), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -363,10 +371,9 @@ begin D => (others => '0'), INMODE => "00000", MULTSIGNIN => '0', - OPMODE => "0110101", + OPMODE => "1010101", P => m11_p, - PCIN => (others => '0'), - PCOUT => m11_pc, + PCIN => m10_pc, RSTA => '0', RSTALLCARRYIN => '0', RSTALUMODE => '0', @@ -390,16 +397,17 @@ begin CARRYINSELREG => 0, CREG => 0, INMODEREG => 0, + MREG => 0, OPMODEREG => 0, - PREG => 0 + PREG => 1 ) port map ( - A => "0000000000000" & m_in.data1(39 downto 23), + A => 6x"0" & m_in.data1(47 downto 24), ACIN => (others => '0'), ALUMODE => "0000", B => '0' & m_in.data2(50 downto 34), BCIN => (others => '0'), - C => x"0000" & '0' & m03_p(36 downto 6), + C => 24x"0" & addend(81 downto 58), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -414,8 +422,8 @@ begin CECTRL => '0', CED => '0', CEINMODE => '0', - CEM => m_in.valid, - CEP => '0', + CEM => '0', + CEP => m_in.valid, CLK => clk, D => (others => '0'), INMODE => "00000", @@ -445,17 +453,19 @@ begin BREG => 0, CARRYINREG => 0, CARRYINSELREG => 0, + CREG => 0, INMODEREG => 0, + MREG => 1, OPMODEREG => 0, PREG => 0 ) port map ( - A => "0000000000000" & m_in.data1(39 downto 23), + A => 6x"0" & m_in.data1(47 downto 24), ACIN => (others => '0'), ALUMODE => "0000", B => "00000" & m_in.data2(63 downto 51), BCIN => (others => '0'), - C => x"0000000" & "000" & addend(90 downto 74), + C => (others => '0'), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -465,7 +475,7 @@ begin CEALUMODE => '0', CEB1 => '0', CEB2 => '0', - CEC => '1', + CEC => '0', CECARRYIN => '0', CECTRL => '0', CED => '0', @@ -476,10 +486,9 @@ begin D => (others => '0'), INMODE => "00000", MULTSIGNIN => '0', - OPMODE => "0110101", + OPMODE => "1010101", P => m13_p, - PCIN => (others => '0'), - PCOUT => m13_pc, + PCIN => m12_pc, RSTA => '0', RSTALLCARRYIN => '0', RSTALUMODE => '0', @@ -501,12 +510,14 @@ begin BREG => 0, CARRYINREG => 0, CARRYINSELREG => 0, + CREG => 0, INMODEREG => 0, + MREG => 0, OPMODEREG => 0, - PREG => 0 + PREG => 1 ) port map ( - A => "000000" & m_in.data1(63 downto 40), + A => 14x"0" & m_in.data1(63 downto 48), ACIN => (others => '0'), ALUMODE => "0000", B => '0' & m_in.data2(16 downto 0), @@ -521,20 +532,21 @@ begin CEALUMODE => '0', CEB1 => '0', CEB2 => '0', - CEC => '1', + CEC => '0', CECARRYIN => '0', CECTRL => '0', CED => '0', CEINMODE => '0', - CEM => m_in.valid, - CEP => '0', + CEM => '0', + CEP => m_in.valid, CLK => clk, D => (others => '0'), INMODE => "00000", MULTSIGNIN => '0', - OPMODE => "0010101", + OPMODE => "0000101", P => m20_p, - PCIN => m11_pc, + PCIN => (others => '0'), + PCOUT => m20_pc, RSTA => '0', RSTALLCARRYIN => '0', RSTALUMODE => '0', @@ -556,12 +568,14 @@ begin BREG => 0, CARRYINREG => 0, CARRYINSELREG => 0, + CREG => 0, INMODEREG => 0, + MREG => 1, OPMODEREG => 0, PREG => 0 ) port map ( - A => "000000" & m_in.data1(63 downto 40), + A => 14x"0" & m_in.data1(63 downto 48), ACIN => (others => '0'), ALUMODE => "0000", B => '0' & m_in.data2(33 downto 17), @@ -576,7 +590,7 @@ begin CEALUMODE => '0', CEB1 => '0', CEB2 => '0', - CEC => '1', + CEC => '0', CECARRYIN => '0', CECTRL => '0', CED => '0', @@ -587,9 +601,9 @@ begin D => (others => '0'), INMODE => "00000", MULTSIGNIN => '0', - OPMODE => "0010101", + OPMODE => "1010101", P => m21_p, - PCIN => m12_pc, + PCIN => m20_pc, RSTA => '0', RSTALLCARRYIN => '0', RSTALUMODE => '0', @@ -611,17 +625,19 @@ begin BREG => 0, CARRYINREG => 0, CARRYINSELREG => 0, + CREG => 0, INMODEREG => 0, + MREG => 0, OPMODEREG => 0, - PREG => 0 + PREG => 1 ) port map ( - A => "000000" & m_in.data1(63 downto 40), + A => 14x"0" & m_in.data1(63 downto 48), ACIN => (others => '0'), ALUMODE => "0000", B => '0' & m_in.data2(50 downto 34), BCIN => (others => '0'), - C => (others => '0'), + C => "00" & addend(127 downto 82), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -631,20 +647,21 @@ begin CEALUMODE => '0', CEB1 => '0', CEB2 => '0', - CEC => '1', + CEC => '0', CECARRYIN => '0', CECTRL => '0', CED => '0', CEINMODE => '0', - CEM => m_in.valid, - CEP => '0', + CEM => '0', + CEP => m_in.valid, CLK => clk, D => (others => '0'), INMODE => "00000", MULTSIGNIN => '0', - OPMODE => "0010101", + OPMODE => "0110101", P => m22_p, - PCIN => m13_pc, + PCIN => (others => '0'), + PCOUT => m22_pc, RSTA => '0', RSTALLCARRYIN => '0', RSTALUMODE => '0', @@ -666,17 +683,19 @@ begin BREG => 0, CARRYINREG => 0, CARRYINSELREG => 0, + CREG => 0, INMODEREG => 0, + MREG => 1, OPMODEREG => 0, PREG => 0 ) port map ( - A => "000000" & m_in.data1(63 downto 40), + A => 14x"0" & m_in.data1(63 downto 48), ACIN => (others => '0'), ALUMODE => "0000", B => "00000" & m_in.data2(63 downto 51), BCIN => (others => '0'), - C => x"00" & "000" & addend(127 downto 91), + C => (others => '0'), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -686,7 +705,7 @@ begin CEALUMODE => '0', CEB1 => '0', CEB2 => '0', - CEC => '1', + CEC => '0', CECARRYIN => '0', CECTRL => '0', CED => '0', @@ -697,9 +716,9 @@ begin D => (others => '0'), INMODE => "00000", MULTSIGNIN => '0', - OPMODE => "0110101", + OPMODE => "1010101", P => m23_p, - PCIN => (others => '0'), + PCIN => m22_pc, RSTA => '0', RSTALLCARRYIN => '0', RSTALUMODE => '0', @@ -712,6 +731,17 @@ begin RSTP => '0' ); + pp0 <= std_ulogic_vector(resize(signed(m13_p(37 downto 0) & m12_p(16 downto 0) & + m01_p(40 downto 0) & m00_p(16 downto 0)), 128)); + pp1 <= m23_p(28 downto 0) & m22_p(16 downto 0) & m11_p(40 downto 0) & m10_p(16 downto 0) & 24x"0"; + -- pp2 <= std_ulogic_vector(resize(signed(m03_p(37 downto 0) & m02_p(16 downto 0) & 34x"0"), 128)); + -- pp3 <= std_ulogic_vector(resize(signed(m21_p(34 downto 0) & m20_p(16 downto 0) & 48x"0"), 128)); + + pp23 <= std_ulogic_vector(resize(resize(signed(m03_p(37 downto 0) & m02_p(16 downto 0) & 34x"0"), 100) + + signed(m21_p(34 downto 0) & m20_p(16 downto 0) & 48x"0"), 128)); + + sumlo <= std_ulogic_vector(unsigned('0' & pp0(31 downto 24)) + unsigned('0' & pp1(31 downto 24))); + s0: DSP48E1 generic map ( ACASCREG => 0, @@ -725,16 +755,16 @@ begin INMODEREG => 0, MREG => 0, OPMODEREG => 0, - PREG => 1, + PREG => 0, USE_MULT => "none" ) port map ( - A => m22_p(5 downto 0) & x"0000" & m10_p(34 downto 27), + A => pp0(79 downto 50), ACIN => (others => '0'), ALUMODE => "0000", - B => m10_p(26 downto 9), + B => pp0(49 downto 32), BCIN => (others => '0'), - C => m20_p(39 downto 0) & m02_p(5 downto 0) & "00", + C => pp1(79 downto 32), CARRYCASCIN => '0', CARRYIN => '0', CARRYINSEL => "000", @@ -751,7 +781,7 @@ begin CED => '0', CEINMODE => '0', CEM => '0', - CEP => valid_1, + CEP => '0', CLK => clk, D => (others => '0'), INMODE => "00000", @@ -773,43 +803,43 @@ begin s1: DSP48E1 generic map ( - ACASCREG => 1, + ACASCREG => 0, ALUMODEREG => 0, - AREG => 1, - BCASCREG => 1, - BREG => 1, + AREG => 0, + BCASCREG => 0, + BREG => 0, CARRYINREG => 0, CARRYINSELREG => 0, - CREG => 1, + CREG => 0, INMODEREG => 0, MREG => 0, OPMODEREG => 0, - PREG => 0, + PREG => 1, USE_MULT => "none" ) port map ( - A => x"000" & m22_p(41 downto 24), + A => pp0(127 downto 98), ACIN => (others => '0'), ALUMODE => "0000", - B => m22_p(23 downto 6), + B => pp0(97 downto 80), BCIN => (others => '0'), - C => m23_p(36 downto 0) & x"00" & "0" & m20_p(41 downto 40), + C => pp1(127 downto 80), CARRYCASCIN => '0', CARRYIN => s0_carry(3), CARRYINSEL => "000", CEA1 => '0', - CEA2 => valid_1, + CEA2 => '0', CEAD => '0', CEALUMODE => '0', CEB1 => '0', - CEB2 => valid_1, - CEC => valid_1, + CEB2 => '0', + CEC => '0', CECARRYIN => '0', CECTRL => '0', CED => '0', CEINMODE => '0', CEM => '0', - CEP => '0', + CEP => valid_1, CLK => clk, D => (others => '0'), INMODE => "00000", @@ -829,52 +859,48 @@ begin RSTP => '0' ); - -- mask is 0 for 32-bit ops, 0x0000ffffffff for 64-bit - p0_mask(47 downto 31) <= (others => '0'); - p0_mask(30 downto 0) <= (others => not r32_1); - p0: DSP48E1 generic map ( - ACASCREG => 1, - ALUMODEREG => 1, - AREG => 1, - BCASCREG => 1, - BREG => 1, + ACASCREG => 0, + ALUMODEREG => 0, + AREG => 0, + BCASCREG => 0, + BREG => 0, CARRYINREG => 0, CARRYINSELREG => 0, - CREG => 1, + CREG => 0, INMODEREG => 0, + MASK => x"00007fffffff", MREG => 0, OPMODEREG => 0, - PREG => 0, - SEL_MASK => "C", + PREG => 1, USE_MULT => "none", USE_PATTERN_DETECT => "PATDET" ) port map ( - A => m21_p(22 downto 0) & m03_p(5 downto 0) & '0', + A => pp23(79 downto 50), ACIN => (others => '0'), ALUMODE => "00" & rnot_1 & '0', - B => (others => '0'), + B => pp23(49 downto 32), BCIN => (others => '0'), - C => p0_mask, + C => (others => '0'), CARRYCASCIN => '0', - CARRYIN => '0', + CARRYIN => sumlo(8), CARRYINSEL => "000", CARRYOUT => p0_carry, CEA1 => '0', - CEA2 => valid_1, + CEA2 => '0', CEAD => '0', - CEALUMODE => valid_1, + CEALUMODE => '0', CEB1 => '0', - CEB2 => valid_1, - CEC => valid_1, + CEB2 => '0', + CEC => '0', CECARRYIN => '0', CECTRL => '0', CED => '0', CEINMODE => '0', CEM => '0', - CEP => '0', + CEP => valid_1, CLK => clk, D => (others => '0'), INMODE => "00000", @@ -915,10 +941,10 @@ begin USE_PATTERN_DETECT => "PATDET" ) port map ( - A => x"0000000" & '0' & m21_p(41), + A => pp23(127 downto 98), ACIN => (others => '0'), ALUMODE => "00" & rnot_1 & '0', - B => m21_p(40 downto 23), + B => pp23(97 downto 80), BCIN => (others => '0'), C => (others => '0'), CARRYCASCIN => '0', @@ -930,7 +956,7 @@ begin CEALUMODE => valid_1, CEB1 => '0', CEB2 => valid_1, - CEC => '0', + CEC => valid_1, CECARRYIN => '0', CECTRL => '0', CED => '0', @@ -958,39 +984,26 @@ begin RSTP => '0' ); - mult_out: process(all) - variable ov : std_ulogic; - begin - -- set overflow if the high bits are neither all zeroes nor all ones - if req_32bit = '0' then - ov := not ((p1_pat and p0_pat) or (p1_patb and p0_patb)); - else - ov := not ((p1_pat and p0_pat and not product(31)) or - (p1_patb and p0_patb and product(31))); - end if; - ovf_in <= ov; - - m_out.result <= product; - m_out.overflow <= overflow; - end process; - process(clk) begin if rising_edge(clk) then - if rnot_1 = '0' then - product(31 downto 0) <= m10_p(8 downto 0) & m01_p(5 downto 0) & m00_p(16 downto 0); - else - product(31 downto 0) <= not (m10_p(8 downto 0) & m01_p(5 downto 0) & m00_p(16 downto 0)); + if valid_1 = '1' then + if rnot_1 = '0' then + product(31 downto 0) <= sumlo(7 downto 0) & pp0(23 downto 0); + else + product(31 downto 0) <= not (sumlo(7 downto 0) & pp0(23 downto 0)); + end if; end if; m_out.valid <= valid_1; valid_1 <= m_in.valid; - req_32bit <= r32_1; - r32_1 <= m_in.is_32bit; rnot_1 <= m_in.not_result; - overflow <= ovf_in; + overflow <= not ((p1_pat and p0_pat) or (p1_patb and p0_patb)); end if; end process; + m_out.result <= product; + m_out.overflow <= overflow; + end architecture behaviour; library ieee;