From f77e7c4e9dff80f8c478851b826e45f13a13cfe0 Mon Sep 17 00:00:00 2001 From: Tristan Gingold Date: Sat, 16 Nov 2019 13:37:38 +0100 Subject: synth: handle static mul sgn sgn. --- src/synth/synth-ieee-numeric_std.adb | 55 ++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) (limited to 'src/synth/synth-ieee-numeric_std.adb') diff --git a/src/synth/synth-ieee-numeric_std.adb b/src/synth/synth-ieee-numeric_std.adb index 096e7fd9f..738146014 100644 --- a/src/synth/synth-ieee-numeric_std.adb +++ b/src/synth/synth-ieee-numeric_std.adb @@ -183,4 +183,59 @@ package body Synth.Ieee.Numeric_Std is return Res; end Mul_Uns_Uns; + function Mul_Sgn_Sgn (L, R : Std_Logic_Vector) return Std_Logic_Vector + is + pragma Assert (L'First = 1); + pragma Assert (R'First = 1); + Res : Std_Logic_Vector (1 .. L'Last + R'Last); + Lb, Rb, Vb, Carry : Sl_X01; + begin + if L'Last < 1 or R'Last < 1 then + return Null_Vec; + end if; + Res := (others => '0'); + -- Shift and add L, do not consider (yet) the sign bit of R. + for I in 0 .. R'Last - 2 loop + Rb := Sl_To_X01 (R (R'Last - I)); + if Rb = '1' then + -- Compute res := res + shift_left (l, i). + Carry := '0'; + for J in 0 .. L'Last - 1 loop + Lb := L (L'Last - J); + Vb := Res (Res'Last - (I + J)); + Res (Res'Last - (I + J)) := Compute_Sum (Carry, Vb, Lb); + Carry := Compute_Carry (Carry, Vb, Lb); + end loop; + -- Sign extend and propagate carry. + Lb := R (1); + for J in I + L'Last .. Res'Last - 1 loop + Vb := Res (Res'Last - J); + Res (Res'Last - J) := Compute_Sum (Carry, Vb, Lb); + Carry := Compute_Carry (Carry, Vb, Lb); + end loop; + elsif Rb = 'X' then + null; + -- assert NO_WARNING + -- report "NUMERIC_STD.""*"": non logical value detected" + -- severity warning; + end if; + end loop; + if R (1) = '1' then + -- R is a negative number. It is considered as: + -- -2**n + (Rn-1 Rn-2 ... R0). + -- Compute res := res - 2**n * l. + Carry := '1'; + for I in 0 .. L'Last - 1 loop + Vb := Res (Res'Last - (R'Last - 1 + I)); + Lb := Not_Table (L (L'Last - I)); + Res (Res'Last - (R'Last - 1 + I)) := Compute_Sum (Carry, Vb, Lb); + Carry := Compute_Carry (Carry, Vb, Lb); + end loop; + Vb := Res (1); + Lb := Not_Table (L (1)); + Res (1) := Compute_Sum (Carry, Vb, Lb); + end if; + return Res; + end Mul_Sgn_Sgn; + end Synth.Ieee.Numeric_Std; -- cgit v1.2.3