From beb5cb55a537086dd066aca4e29248cbac44a417 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Povi=C5=A1er?= <povik@cutebit.org>
Date: Wed, 22 Nov 2023 14:57:13 +0100
Subject: [PATCH] booth: Expose `-lowpower` option
---
passes/techmap/booth.cc | 34 ++++++++++++++++++++++++++--------
1 file changed, 26 insertions(+), 8 deletions(-)
diff --git a/passes/techmap/booth.cc b/passes/techmap/booth.cc
index 0830f9766..581400236 100644
--- a/passes/techmap/booth.cc
+++ b/passes/techmap/booth.cc
@@ -66,6 +66,7 @@ struct BoothPassWorker {
RTLIL::Module *module;
SigMap sigmap;
int booth_counter;
+ bool lowpower = false;
BoothPassWorker(RTLIL::Module *module) : module(module), sigmap(module) { booth_counter = 0; }
@@ -276,12 +277,20 @@ struct BoothPassWorker {
}
log_assert(GetSize(Y) == required_op_size);
- CreateBoothMult(module,
- A, // multiplicand
- B, // multiplier(scanned)
- Y, // result
- is_signed
- );
+ if (!lowpower)
+ CreateBoothMult(module,
+ A, // multiplicand
+ B, // multiplier(scanned)
+ Y, // result
+ is_signed
+ );
+ else
+ CreateBoothLowpowerMult(module,
+ A, // multiplicand
+ B, // multiplier(scanned)
+ Y, // result
+ is_signed
+ );
module->remove(cell);
booth_counter++;
@@ -904,12 +913,15 @@ struct BoothPassWorker {
}
/*
- Signed Multiplier
+ Low-power Multiplier
*/
- void CreateBoothSMult(RTLIL::Module *module, SigSpec X, SigSpec Y, SigSpec Z)
+ void CreateBoothLowpowerMult(RTLIL::Module *module, SigSpec X, SigSpec Y, SigSpec Z, bool is_signed)
{ // product
int x_sz = X.size(), y_sz = Y.size(), z_sz = Z.size();
+ if (!is_signed)
+ log_error("Low-power Booth architecture is only supported on signed multipliers.\n");
+
unsigned enc_count = (y_sz / 2) + (((y_sz % 2) != 0) ? 1 : 0);
int dec_count = x_sz + 1;
@@ -1118,8 +1130,13 @@ struct BoothPass : public Pass {
log_header(design, "Executing BOOTH pass (map to Booth multipliers).\n");
size_t argidx;
+ bool lowpower = false;
for (argidx = 1; argidx < args.size(); argidx++) {
break;
+ if (args[argidx] == "-lowpower")
+ lowpower = true;
+ else
+ break;
}
extra_args(args, argidx, design);
@@ -1128,6 +1145,7 @@ struct BoothPass : public Pass {
for (auto mod : design->selected_modules()) {
if (!mod->has_processes_warn()) {
BoothPassWorker worker(mod);
+ worker.lowpower = lowpower;
worker.run();
total += worker.booth_counter;
}