JPEG optimisations

source/fpga/modules/camera/jpeg_encoder/jenc/bit_pack.sv

@@ -0,0 +1,139 @@
+/*
+ * Authored by: Robert Metchev / Chips & Scripts (rmetchev@ieee.org)
+ *
+ * CERN Open Hardware Licence Version 2 - Permissive
+ *
+ * Copyright (C) 2024 Robert Metchev
+ */
+module bit_pack (
+    //packed code+coeff
+    input   logic [63:0]            in_data,
+    input   logic [6:0]             in_nbits,
+    input   logic                   in_tlast,
+    input   logic                   in_valid,
+    output  logic                   in_hold,
+
+    output  logic [31:0]            out_data,
+    output  logic [2:0]             out_nbytes,
+    output  logic                   out_tlast,
+    output  logic                   out_valid,
+    input   logic                   out_hold,
+
+    input   logic                   clk,
+    input   logic                   resetn
+);
+
+// 1.)  64-bit to 32-bit align: There will be extremely rarely more than 32 bits.
+//      Stall during 1st 32 bits.
+logic [31:0]            in32_data;
+logic [5:0]             in32_nbits;
+logic                   in32_tlast;
+logic                   in32_valid;
+logic                   in32_hold;
+logic                   long_in; 
+
+always @(posedge clk)
+if (!resetn) begin
+    in32_valid <= 0;
+    long_in <= 0;
+end
+else if (~(in32_hold & in32_valid)) begin
+    in32_valid <= in_valid;
+
+    if (long_in)
+        long_in <= 0;
+    else if (in_valid & in_nbits > 32)
+        long_in <= 1;
+end
+
+always @(posedge clk)
+if (~(in32_hold & in32_valid))
+    if (long_in) begin
+        in32_nbits <= in_nbits - 32;
+        in32_data <= in_data;
+        in32_tlast <= in_tlast;
+    end
+    else if (in_valid)
+        if (in_nbits > 32)  begin
+            in32_nbits <= 32;
+            in32_data <= in_data >> 32;
+            in32_tlast <= 0;
+        end
+        else begin
+            in32_nbits <= in_nbits;
+            in32_data <= in_data >> 32;
+            in32_tlast <= in_tlast;
+        end
+
+// Stall to split 32+ into 32 + remainder
+always_comb in_hold = (in32_hold & in32_valid) | (~long_in & in_nbits > 32); // goes out
+
+
+// 2.)  incoming: 32 bits max = 4 bytes
+//      send data when more than 31 bits in storage
+logic [5:0]             bit_count, next_bit_count, next_bit_count_incr, next_bit_count_decr;
+logic [63:0]            bit_packer, next_bit_packer, next_bit_packer_load;
+logic [5:0]             next_bit_packer_shift;
+logic                   tlast_cycle, next_tlast_cycle;
+logic                   next_out_tlast;
+
+always_comb out_data = (bit_packer >> 32) | (out_tlast ? (32'hffffffff >> bit_count) : 0);
+always_comb next_bit_count = bit_count + next_bit_count_incr - next_bit_count_decr;
+always_comb next_bit_packer = (bit_packer << next_bit_packer_shift) | (next_bit_packer_load << (32 + next_bit_count_decr - bit_count));
+
+always_comb begin
+    if (out_tlast) begin
+        next_bit_count_decr = bit_count;
+        next_bit_packer_shift = 32;
+    end
+    else if (bit_count >= 32) begin
+        next_bit_count_decr = 32;
+        next_bit_packer_shift = 32;
+    end
+    else begin
+        next_bit_count_decr = 0;
+        next_bit_packer_shift = 0;
+    end
+
+    if (in32_valid & ~in32_hold) begin
+        next_bit_count_incr = in32_nbits;
+        next_bit_packer_load = in32_data;
+    end
+    else begin
+        next_bit_count_incr = 0;
+        next_bit_packer_load = 0;
+    end
+
+    if (tlast_cycle)
+        next_tlast_cycle = ~out_tlast;
+    else if (in32_valid)
+        next_tlast_cycle = in32_tlast;
+    else
+        next_tlast_cycle = tlast_cycle;
+end
+
+always @(posedge clk)
+if (!resetn) begin
+    bit_count <= 0;
+    tlast_cycle <= 0;
+    out_tlast <= 0;
+    out_valid <= 0;
+    bit_packer <= 0;
+end
+else if (~(out_hold & out_valid)) begin   
+    bit_count <= next_bit_count;
+    tlast_cycle <= next_tlast_cycle;
+
+    out_tlast <= next_tlast_cycle & next_bit_count <= 32;
+    out_valid <= (next_tlast_cycle & next_bit_count <= 32) | next_bit_count >= 32; //always_comb out_valid = out_tlast | bit_count >= 32;
+
+    bit_packer <= next_bit_packer;
+end
+
+always @(posedge clk)
+if (~(out_hold & out_valid))
+    out_nbytes <= (next_tlast_cycle & next_bit_count <= 32) ? (next_bit_count + 7) >> 3 : 4; // always_comb out_nbytes = out_tlast ? (bit_count + 7) >> 3 : 4;
+
+always_comb in32_hold = (out_hold & out_valid) | (tlast_cycle & ~out_tlast);
+
+endmodule

source/fpga/modules/camera/jpeg_encoder/jenc/byte_pack.sv

@@ -0,0 +1,85 @@
+/*
+ * Authored by: Robert Metchev / Chips & Scripts (rmetchev@ieee.org)
+ *
+ * CERN Open Hardware Licence Version 2 - Permissive
+ *
+ * Copyright (C) 2024 Robert Metchev
+ */
+module byte_pack (
+    //packed code+coeff
+    input   logic [5:0]             codecoeff_length,
+    input   logic [51:0]            codecoeff,
+    input   logic                   codecoeff_tlast,
+    input   logic                   codecoeff_valid,
+    output  logic                   codecoeff_hold,
+
+    output  logic [31:0]            out_data,
+    output  logic                   out_tlast,
+    output  logic                   out_valid,
+    input   logic                   out_hold,
+
+    input   logic                   clk,
+    input   logic                   resetn
+);
+
+// Pack up to 52 bits into 4 byte words
+logic [31:0]            data_0;
+logic [2:0]             nbytes_0;
+logic                   tlast_0;
+logic                   valid_0;
+logic                   hold_0;
+
+bit_pack bit_pack_0 (
+    .in_data                ({codecoeff, 12'h0}),
+    .in_nbits               ({1'b0, codecoeff_length}),
+    .in_tlast               (codecoeff_tlast),
+    .in_valid               (codecoeff_valid),
+    .in_hold                (codecoeff_hold),
+
+    .out_data               (data_0),
+    .out_nbytes             (nbytes_0),
+    .out_tlast              (tlast_0),
+    .out_valid              (valid_0),
+    .out_hold               (hold_0 & valid_0),
+
+    .*
+);
+
+// pad 0xFF with 0x00
+logic [63:0]            data_1;
+logic [3:0]             nbytes_1;
+logic                   tlast_1;
+logic                   valid_1;
+logic                   hold_1;
+
+ff00 ff00 ( 
+    .in_data                (data_0),
+    .in_nbytes              (nbytes_0),
+    .in_tlast               (tlast_0),
+    .in_valid               (valid_0),
+    .in_hold                (hold_0),
+
+    .out_data               (data_1),
+    .out_nbytes             (nbytes_1),
+    .out_tlast              (tlast_1),
+    .out_valid              (valid_1),
+    .out_hold               (hold_1 & valid_1),
+
+    .*
+);
+
+// Pack up to 8 bytes into 4 byte words
+bit_pack bit_pack_1 (
+    .in_data                (data_1),
+    .in_nbits               ({nbytes_1, 3'h0}),     // bytes -> bits
+    .in_tlast               (tlast_1),
+    .in_valid               (valid_1),
+    .in_hold                (hold_1),
+
+    .out_nbytes             ( ),    // always full 32 bits/4 bytes
+    .out_hold               (out_hold & out_valid),
+
+    .*
+);
+
+endmodule