rtl/gfx: implement fixed-point division

2 files changed, 62 insertions, 0 deletions

diff --git a/rtl/gfx/gfx_defs.sv b/rtl/gfx/gfx_defs.sv
index 429928c..bffbb1f 100644
--- a/rtl/gfx/gfx_defs.sv
+++ b/rtl/gfx/gfx_defs.sv
@@ -59,6 +59,7 @@ typedef struct packed
 
 `define FIXED_FRAC 16
 
+`define FIXED_DIV_STAGES     8
 `define FIXED_FMA_STAGES     5
 `define FIXED_FMA_DOT_STAGES (2 * `FIXED_FMA_STAGES)
 `define LERP_STAGES          `FIXED_FMA_DOT_STAGES
diff --git a/rtl/gfx/gfx_fixed_div.sv b/rtl/gfx/gfx_fixed_div.sv
new file mode 100644
index 0000000..320d9b8
--- /dev/null
+++ b/rtl/gfx/gfx_fixed_div.sv
@@ -0,0 +1,61 @@
+`include "gfx/gfx_defs.sv"
+
+module gfx_fixed_div
+(
+	input  logic  clk,
+
+	input  fixed  z,
+	              d,
+	input  logic  stall,
+
+	output fixed  q
+);
+
+	localparam DIV_BITS = `FIXED_FRAC + $bits(fixed);
+
+	logic signed[DIV_BITS - 1:0] z_int, q_int;
+
+	assign q = q_int[$bits(q) - 1:0];
+	assign z_int = {z, {`FIXED_FRAC{1'b0}}};
+
+`ifndef VERILATOR
+	lpm_divide div
+	(
+		.aclr(0),
+		.clock(clk),
+		.clken(!stall),
+		.numer(z_int),
+		.denom(d),
+		.remain(),
+		.quotient(q_int)
+	);
+
+	defparam
+		div.lpm_widthn          = DIV_BITS,
+		div.lpm_widthd          = $bits(fixed),
+		div.lpm_nrepresentation = "SIGNED",
+		div.lpm_nrepresentation = "SIGNED",
+		div.lpm_pipeline        = `FIXED_DIV_STAGES;
+`else
+	fixed d_hold;
+	logic signed[DIV_BITS - 1:0] d_int_hold, z_int_hold;
+
+	assign q_int = z_int_hold / d_int_hold;
+	assign d_int_hold = {{`FIXED_FRAC{d_hold[$bits(d_hold) - 1]}}, d_hold};
+
+	gfx_pipes #(.WIDTH($bits(z_int)), .DEPTH(`FIXED_DIV_STAGES)) z_int_pipes
+	(
+		.in(z_int),
+		.out(z_int_hold),
+		.*
+	);
+
+	gfx_pipes #(.WIDTH($bits(d)), .DEPTH(`FIXED_DIV_STAGES)) d_pipes
+	(
+		.in(d),
+		.out(d_hold),
+		.*
+	);
+`endif
+
+endmodule