Add support for ice40 signed multipliers

diff --git a/passes/pmgen/ice40_dsp.cc b/passes/pmgen/ice40_dsp.cc
index 39d033a04f449e49e863d8ebf98adc23fdfbd728..963a7d7a1b33e9fc96eb3df7b1d2ca01a8658031 100644 (file)
--- a/passes/pmgen/ice40_dsp.cc
+++ b/passes/pmgen/ice40_dsp.cc
@@ -62,32 +62,27 @@ void create_ice40_dsp(ice40_dsp_pm &pm)
                return;
        }
 
-       bool mul_signed = st.mul->getParam("\\A_SIGNED").as_bool();
-
-       if (mul_signed) {
-               log("  inference of signed iCE40 DSP arithmetic is currently not supported.\n");
-               return;
-       }
-
-       log("  replacing $mul with SB_MAC16 cell.\n");
+       log("  replacing %s with SB_MAC16 cell.\n", log_id(st.mul->type));
 
        Cell *cell = pm.module->addCell(NEW_ID, "\\SB_MAC16");
        pm.module->swap_names(cell, st.mul);
 
        // SB_MAC16 Input Interface
+       bool a_signed = st.mul->getParam("\\A_SIGNED").as_bool();
+       bool b_signed = st.mul->getParam("\\B_SIGNED").as_bool();
 
        SigSpec A = st.sigA;
-       A.extend_u0(16, mul_signed);
+       A.extend_u0(16, a_signed);
 
        SigSpec B = st.sigB;
-       B.extend_u0(16, mul_signed);
+       B.extend_u0(16, b_signed);
 
        SigSpec CD;
        if (st.muxA)
                CD = st.muxA->getPort("\\B");
        if (st.muxB)
                CD = st.muxB->getPort("\\A");
-       CD.extend_u0(32, mul_signed);
+       CD.extend_u0(32, a_signed && b_signed);
 
        cell->setPort("\\A", A);
        cell->setPort("\\B", B);
@@ -198,8 +193,8 @@ void create_ice40_dsp(ice40_dsp_pm &pm)
        cell->setParam("\\BOTADDSUB_CARRYSELECT", Const(0, 2));
 
        cell->setParam("\\MODE_8x8", State::S0);
-       cell->setParam("\\A_SIGNED", mul_signed ? State::S1 : State::S0);
-       cell->setParam("\\B_SIGNED", mul_signed ? State::S1 : State::S0);
+       cell->setParam("\\A_SIGNED", a_signed);
+       cell->setParam("\\B_SIGNED", b_signed);
 
        pm.autoremove(st.mul);
        pm.autoremove(st.ffY);