From 17812a1560b52b997889d606115266528cdc871f Mon Sep 17 00:00:00 2001
From: David Shah <dave@ds0.me>
Date: Mon, 7 Dec 2020 13:27:17 +0000
Subject: nexus: Add LRAM inference

Signed-off-by: David Shah <dave@ds0.me>
---
 techlibs/nexus/Makefile.inc   |   3 +
 techlibs/nexus/lrams.txt      |  22 ++++++++
 techlibs/nexus/lrams_init.vh  | 128 ++++++++++++++++++++++++++++++++++++++++++
 techlibs/nexus/lrams_map.v    |  56 ++++++++++++++++++
 techlibs/nexus/synth_nexus.cc |  19 ++++++-
 5 files changed, 227 insertions(+), 1 deletion(-)
 create mode 100644 techlibs/nexus/lrams.txt
 create mode 100644 techlibs/nexus/lrams_init.vh
 create mode 100644 techlibs/nexus/lrams_map.v

(limited to 'techlibs')

diff --git a/techlibs/nexus/Makefile.inc b/techlibs/nexus/Makefile.inc
index c9a9ad4ff..9828d32c1 100644
--- a/techlibs/nexus/Makefile.inc
+++ b/techlibs/nexus/Makefile.inc
@@ -9,6 +9,9 @@ $(eval $(call add_share_file,share/nexus,techlibs/nexus/lutrams.txt))
 $(eval $(call add_share_file,share/nexus,techlibs/nexus/brams_init.vh))
 $(eval $(call add_share_file,share/nexus,techlibs/nexus/brams_map.v))
 $(eval $(call add_share_file,share/nexus,techlibs/nexus/brams.txt))
+$(eval $(call add_share_file,share/nexus,techlibs/nexus/lrams_init.vh))
+$(eval $(call add_share_file,share/nexus,techlibs/nexus/lrams_map.v))
+$(eval $(call add_share_file,share/nexus,techlibs/nexus/lrams.txt))
 $(eval $(call add_share_file,share/nexus,techlibs/nexus/arith_map.v))
 $(eval $(call add_share_file,share/nexus,techlibs/nexus/latches_map.v))
 $(eval $(call add_share_file,share/nexus,techlibs/nexus/dsp_map.v))
diff --git a/techlibs/nexus/lrams.txt b/techlibs/nexus/lrams.txt
new file mode 100644
index 000000000..481629b98
--- /dev/null
+++ b/techlibs/nexus/lrams.txt
@@ -0,0 +1,22 @@
+bram $__NX_PDPSC512K
+  init 1
+
+  abits 14
+  dbits 32
+
+  groups 2
+  ports 1 1
+  wrmode 1 0
+  enable 4 1
+  transp 0 0
+  clocks 2 2
+  clkpol 2 2
+endbram
+
+match $__NX_PDPSC512K
+  # explicitly requested LRAM only, due to limited availability and
+  # slower Fmax
+  attribute lram
+  shuffle_enable A
+  make_transp
+endmatch
diff --git a/techlibs/nexus/lrams_init.vh b/techlibs/nexus/lrams_init.vh
new file mode 100644
index 000000000..31a7ba4a8
--- /dev/null
+++ b/techlibs/nexus/lrams_init.vh
@@ -0,0 +1,128 @@
+.INITVAL_00($sformatf("0x%05120x", permute_init(INIT[0 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_01($sformatf("0x%05120x", permute_init(INIT[1 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_02($sformatf("0x%05120x", permute_init(INIT[2 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_03($sformatf("0x%05120x", permute_init(INIT[3 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_04($sformatf("0x%05120x", permute_init(INIT[4 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_05($sformatf("0x%05120x", permute_init(INIT[5 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_06($sformatf("0x%05120x", permute_init(INIT[6 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_07($sformatf("0x%05120x", permute_init(INIT[7 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_08($sformatf("0x%05120x", permute_init(INIT[8 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_09($sformatf("0x%05120x", permute_init(INIT[9 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_0A($sformatf("0x%05120x", permute_init(INIT[10 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_0B($sformatf("0x%05120x", permute_init(INIT[11 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_0C($sformatf("0x%05120x", permute_init(INIT[12 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_0D($sformatf("0x%05120x", permute_init(INIT[13 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_0E($sformatf("0x%05120x", permute_init(INIT[14 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_0F($sformatf("0x%05120x", permute_init(INIT[15 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_10($sformatf("0x%05120x", permute_init(INIT[16 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_11($sformatf("0x%05120x", permute_init(INIT[17 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_12($sformatf("0x%05120x", permute_init(INIT[18 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_13($sformatf("0x%05120x", permute_init(INIT[19 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_14($sformatf("0x%05120x", permute_init(INIT[20 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_15($sformatf("0x%05120x", permute_init(INIT[21 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_16($sformatf("0x%05120x", permute_init(INIT[22 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_17($sformatf("0x%05120x", permute_init(INIT[23 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_18($sformatf("0x%05120x", permute_init(INIT[24 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_19($sformatf("0x%05120x", permute_init(INIT[25 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_1A($sformatf("0x%05120x", permute_init(INIT[26 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_1B($sformatf("0x%05120x", permute_init(INIT[27 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_1C($sformatf("0x%05120x", permute_init(INIT[28 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_1D($sformatf("0x%05120x", permute_init(INIT[29 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_1E($sformatf("0x%05120x", permute_init(INIT[30 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_1F($sformatf("0x%05120x", permute_init(INIT[31 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_20($sformatf("0x%05120x", permute_init(INIT[32 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_21($sformatf("0x%05120x", permute_init(INIT[33 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_22($sformatf("0x%05120x", permute_init(INIT[34 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_23($sformatf("0x%05120x", permute_init(INIT[35 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_24($sformatf("0x%05120x", permute_init(INIT[36 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_25($sformatf("0x%05120x", permute_init(INIT[37 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_26($sformatf("0x%05120x", permute_init(INIT[38 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_27($sformatf("0x%05120x", permute_init(INIT[39 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_28($sformatf("0x%05120x", permute_init(INIT[40 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_29($sformatf("0x%05120x", permute_init(INIT[41 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_2A($sformatf("0x%05120x", permute_init(INIT[42 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_2B($sformatf("0x%05120x", permute_init(INIT[43 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_2C($sformatf("0x%05120x", permute_init(INIT[44 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_2D($sformatf("0x%05120x", permute_init(INIT[45 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_2E($sformatf("0x%05120x", permute_init(INIT[46 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_2F($sformatf("0x%05120x", permute_init(INIT[47 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_30($sformatf("0x%05120x", permute_init(INIT[48 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_31($sformatf("0x%05120x", permute_init(INIT[49 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_32($sformatf("0x%05120x", permute_init(INIT[50 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_33($sformatf("0x%05120x", permute_init(INIT[51 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_34($sformatf("0x%05120x", permute_init(INIT[52 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_35($sformatf("0x%05120x", permute_init(INIT[53 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_36($sformatf("0x%05120x", permute_init(INIT[54 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_37($sformatf("0x%05120x", permute_init(INIT[55 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_38($sformatf("0x%05120x", permute_init(INIT[56 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_39($sformatf("0x%05120x", permute_init(INIT[57 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_3A($sformatf("0x%05120x", permute_init(INIT[58 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_3B($sformatf("0x%05120x", permute_init(INIT[59 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_3C($sformatf("0x%05120x", permute_init(INIT[60 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_3D($sformatf("0x%05120x", permute_init(INIT[61 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_3E($sformatf("0x%05120x", permute_init(INIT[62 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_3F($sformatf("0x%05120x", permute_init(INIT[63 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_40($sformatf("0x%05120x", permute_init(INIT[64 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_41($sformatf("0x%05120x", permute_init(INIT[65 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_42($sformatf("0x%05120x", permute_init(INIT[66 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_43($sformatf("0x%05120x", permute_init(INIT[67 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_44($sformatf("0x%05120x", permute_init(INIT[68 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_45($sformatf("0x%05120x", permute_init(INIT[69 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_46($sformatf("0x%05120x", permute_init(INIT[70 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_47($sformatf("0x%05120x", permute_init(INIT[71 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_48($sformatf("0x%05120x", permute_init(INIT[72 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_49($sformatf("0x%05120x", permute_init(INIT[73 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_4A($sformatf("0x%05120x", permute_init(INIT[74 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_4B($sformatf("0x%05120x", permute_init(INIT[75 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_4C($sformatf("0x%05120x", permute_init(INIT[76 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_4D($sformatf("0x%05120x", permute_init(INIT[77 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_4E($sformatf("0x%05120x", permute_init(INIT[78 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_4F($sformatf("0x%05120x", permute_init(INIT[79 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_50($sformatf("0x%05120x", permute_init(INIT[80 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_51($sformatf("0x%05120x", permute_init(INIT[81 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_52($sformatf("0x%05120x", permute_init(INIT[82 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_53($sformatf("0x%05120x", permute_init(INIT[83 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_54($sformatf("0x%05120x", permute_init(INIT[84 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_55($sformatf("0x%05120x", permute_init(INIT[85 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_56($sformatf("0x%05120x", permute_init(INIT[86 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_57($sformatf("0x%05120x", permute_init(INIT[87 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_58($sformatf("0x%05120x", permute_init(INIT[88 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_59($sformatf("0x%05120x", permute_init(INIT[89 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_5A($sformatf("0x%05120x", permute_init(INIT[90 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_5B($sformatf("0x%05120x", permute_init(INIT[91 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_5C($sformatf("0x%05120x", permute_init(INIT[92 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_5D($sformatf("0x%05120x", permute_init(INIT[93 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_5E($sformatf("0x%05120x", permute_init(INIT[94 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_5F($sformatf("0x%05120x", permute_init(INIT[95 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_60($sformatf("0x%05120x", permute_init(INIT[96 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_61($sformatf("0x%05120x", permute_init(INIT[97 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_62($sformatf("0x%05120x", permute_init(INIT[98 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_63($sformatf("0x%05120x", permute_init(INIT[99 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_64($sformatf("0x%05120x", permute_init(INIT[100 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_65($sformatf("0x%05120x", permute_init(INIT[101 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_66($sformatf("0x%05120x", permute_init(INIT[102 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_67($sformatf("0x%05120x", permute_init(INIT[103 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_68($sformatf("0x%05120x", permute_init(INIT[104 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_69($sformatf("0x%05120x", permute_init(INIT[105 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_6A($sformatf("0x%05120x", permute_init(INIT[106 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_6B($sformatf("0x%05120x", permute_init(INIT[107 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_6C($sformatf("0x%05120x", permute_init(INIT[108 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_6D($sformatf("0x%05120x", permute_init(INIT[109 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_6E($sformatf("0x%05120x", permute_init(INIT[110 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_6F($sformatf("0x%05120x", permute_init(INIT[111 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_70($sformatf("0x%05120x", permute_init(INIT[112 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_71($sformatf("0x%05120x", permute_init(INIT[113 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_72($sformatf("0x%05120x", permute_init(INIT[114 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_73($sformatf("0x%05120x", permute_init(INIT[115 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_74($sformatf("0x%05120x", permute_init(INIT[116 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_75($sformatf("0x%05120x", permute_init(INIT[117 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_76($sformatf("0x%05120x", permute_init(INIT[118 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_77($sformatf("0x%05120x", permute_init(INIT[119 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_78($sformatf("0x%05120x", permute_init(INIT[120 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_79($sformatf("0x%05120x", permute_init(INIT[121 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_7A($sformatf("0x%05120x", permute_init(INIT[122 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_7B($sformatf("0x%05120x", permute_init(INIT[123 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_7C($sformatf("0x%05120x", permute_init(INIT[124 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_7D($sformatf("0x%05120x", permute_init(INIT[125 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_7E($sformatf("0x%05120x", permute_init(INIT[126 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
+.INITVAL_7F($sformatf("0x%05120x", permute_init(INIT[127 * INIT_CHUNK_SIZE +: INIT_CHUNK_SIZE]))),
diff --git a/techlibs/nexus/lrams_map.v b/techlibs/nexus/lrams_map.v
new file mode 100644
index 000000000..938a0e843
--- /dev/null
+++ b/techlibs/nexus/lrams_map.v
@@ -0,0 +1,56 @@
+module \$__NX_PDPSC512K (CLK2, A1ADDR, A1DATA, A1EN, B1ADDR, B1DATA, B1EN);
+	parameter CFG_ABITS = 14;
+	parameter CFG_DBITS = 32;
+	parameter CFG_ENABLE_A = 4;
+
+	parameter CLKPOL2 = 1;
+	parameter [524287:0] INIT = 524287'b0;
+
+	input CLK2;
+
+	input [CFG_ABITS-1:0] A1ADDR;
+	input [CFG_DBITS-1:0] A1DATA;
+	input [CFG_ENABLE_A-1:0] A1EN;
+
+	input [CFG_ABITS-1:0] B1ADDR;
+	output [CFG_DBITS-1:0] B1DATA;
+	input B1EN;
+
+	wire clk;
+	wire [31:0] rd;
+	assign B1DATA = rd[CFG_DBITS-1:0];
+
+	generate
+		if (CLKPOL2)
+			assign clk = CLK2;
+		else
+			INV clk_inv_i (.A(CLK2), .Z(clk));
+	endgenerate
+
+	wire we = |A1EN;
+
+	localparam INIT_CHUNK_SIZE = 4096;
+
+	function [5119:0] permute_init;
+		input [INIT_CHUNK_SIZE-1:0] chunk;
+		integer i;
+		begin
+			for (i = 0; i < 128; i = i + 1'b1)
+				permute_init[i * 40 +: 40] = {8'b0, chunk[i * 32 +: 32]};
+		end
+	endfunction
+
+	generate
+		PDPSC512K #(
+			.OUTREG("NO_REG"),
+			.ECC_BYTE_SEL("BYTE_EN"),
+`include "lrams_init.vh"
+			.GSR("DISABLED")
+		) _TECHMAP_REPLACE_ (
+			.CLK(clk), .RSTR(1'b0),
+			.DI(A1DATA), .ADW(A1ADDR), .CEW(we), .WE(we), .CSW(1'b1),
+			.ADR(B1ADDR), .DO(rd), .CER(B1EN), .CSR(1'b1),
+		);
+	endgenerate
+
+endmodule
diff --git a/techlibs/nexus/synth_nexus.cc b/techlibs/nexus/synth_nexus.cc
index 9eabbace7..7f36eb282 100644
--- a/techlibs/nexus/synth_nexus.cc
+++ b/techlibs/nexus/synth_nexus.cc
@@ -77,6 +77,11 @@ struct SynthNexusPass : public ScriptPass
 		log("    -nodffe\n");
 		log("        do not use flipflops with CE in output netlist\n");
 		log("\n");
+		log("    -nolram\n");
+		log("        do not use large RAM cells in output netlist\n");
+		log("        note that large RAM must be explicitly requested with a (* lram *)\n");
+		log("        attribute on the memory.\n");
+		log("\n");
 		log("    -nobram\n");
 		log("        do not use block RAM cells in output netlist\n");
 		log("\n");
@@ -101,7 +106,7 @@ struct SynthNexusPass : public ScriptPass
 	}
 
 	string top_opt, json_file, vm_file, family;
-	bool noccu2, nodffe, nobram, nolutram, nowidelut, noiopad, nodsp, flatten, dff, retime, abc9;
+	bool noccu2, nodffe, nolram, nobram, nolutram, nowidelut, noiopad, nodsp, flatten, dff, retime, abc9;
 
 	void clear_flags() override
 	{
@@ -111,6 +116,7 @@ struct SynthNexusPass : public ScriptPass
 		vm_file = "";
 		noccu2 = false;
 		nodffe = false;
+		nolram = false;
 		nobram = false;
 		nolutram = false;
 		nowidelut = false;
@@ -181,6 +187,10 @@ struct SynthNexusPass : public ScriptPass
 				nodffe = true;
 				continue;
 			}
+			if (args[argidx] == "-nolram") {
+				nolram = true;
+				continue;
+			}
 			if (args[argidx] == "-nobram") {
 				nobram = true;
 				continue;
@@ -286,6 +296,13 @@ struct SynthNexusPass : public ScriptPass
 			run("opt_clean");
 		}
 
+		if (!nolram && check_label("map_lram", "(skip if -nolram)"))
+		{
+			run("memory_bram -rules +/nexus/lrams.txt");
+			run("setundef -zero -params t:$__NX_PDPSC512K");
+			run("techmap -map +/nexus/lrams_map.v");
+		}
+
 		if (!nobram && check_label("map_bram", "(skip if -nobram)"))
 		{
 			run("memory_bram -rules +/nexus/brams.txt");
-- 
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