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https://github.com/allaunthefox/Research-Stack.git
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ba203ca971
Ported from ScaleSpaceSynth (WebGPU particle simulator): - 64×64×64 spatial hash, 32 particles/cell, lock-free insertion - Curl noise: divergence-free 3D turbulence - Pairwise forces: attractive (ratio>0.15) + repulsive (ratio<=0.15) - Trilinear density interpolation - HalfLife particle lifecycle - Q16_16 encode/decode for VCN transport Python (spatial_hash_grid.py): 6/6 tests pass 10K particles, neighbor query, forces, 100 sim steps, curl noise verified FPGA (spatial_hash_bram.v): 16×16×16 grid, dual-port BRAM, 27-cycle neighbor scan Density → voltage mode selector (STORE/COMPUTE/APPROX/MORPHIC) Integrated into research_stack_top.v Same pattern as ScaleSpaceSynth GPU: GPU: atomicAdd for lock-free cell assignment FPGA: BRAM read-modify-write for cell assignment Ray: content-addressed ObjectRef for lock-free reads All: partition space → compute density → find structure at multiple scales
321 lines
14 KiB
Verilog
321 lines
14 KiB
Verilog
`timescale 1ns / 1ps
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// Spatial Hash Grid for Tang Nano 9K (GW1NR-9C)
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// Port of ScaleSpaceSynth spatial hash to FPGA.
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//
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// Grid: 16×16×16 = 4096 cells (reduced from 64³ for BRAM budget)
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// Cell cap: 8 particles per cell (reduced from 32)
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// Hash: cellIdx = x[3:0] + y[3:0]*16 + z[3:0]*256
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// Storage: dual-port BRAM — one for cell particle counts, one for neighbor scan
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// Search: 3×3×3 = 27 neighbor cells, sequential scan (27 cycles)
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// Density: particle count per cell
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// Interp: 8-point trilinear weighted average from fractional position
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// Arith: Q16_16 fixed-point throughout
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//
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// FSM: IDLE → INSERT → QUERY → NEIGHBOR_SCAN → INTERPOLATE → DONE
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module spatial_hash_bram (
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input wire clk,
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input wire rst_n,
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// Particle insertion port
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input wire [3:0] particle_x, // particle grid position X (4-bit)
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input wire [3:0] particle_y, // particle grid position Y (4-bit)
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input wire [3:0] particle_z, // particle grid position Z (4-bit)
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input wire particle_valid, // insert trigger (pulse)
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// Query port
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input wire [3:0] query_x, // query grid position X (4-bit)
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input wire [3:0] query_y, // query grid position Y (4-bit)
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input wire [3:0] query_z, // query grid position Z (4-bit)
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input wire query_valid, // query trigger (pulse)
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// Results
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output reg [15:0] cell_density, // particle count at query cell (8-bit used)
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output reg [15:0] neighbor_density, // max density in 3×3×3 neighborhood
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output reg query_done // query complete pulse
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);
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// ── Grid Parameters ───────────────────────────────────────────
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// Grid dimensions: 16 × 16 × 16 = 4096 cells
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// Hash: cellIdx = x + y*16 + z*256 (12-bit index)
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// Each cell stores an 8-bit particle count (cap at 255)
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// ── BRAM: Cell Particle Counts ────────────────────────────────
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// 4096 entries × 8-bit (one BRAM18K on GW1NR-9C)
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reg [7:0] cell_ram [0:4095];
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// Dual-port signals
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reg [11:0] cell_wr_addr;
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reg [7:0] cell_wr_data;
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reg cell_wr_en;
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reg [11:0] cell_rd_addr;
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reg [7:0] cell_rd_data;
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// ── Neighbor BRAM: scan buffer ────────────────────────────────
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// 27 entries × 8-bit (stores densities during neighbor scan)
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reg [7:0] neighbor_ram [0:26];
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reg [4:0] nbr_wr_addr;
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reg [7:0] nbr_wr_data;
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reg nbr_wr_en;
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// ── FSM States ────────────────────────────────────────────────
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localparam S_IDLE = 3'd0;
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localparam S_INSERT = 3'd1; // write particle to cell
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localparam S_INSERT_RD = 3'd2; // read-modify-write (read phase)
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localparam S_QUERY = 3'd3; // read query cell density
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localparam S_NEIGHBOR_SCAN = 3'd4; // scan 3×3×3 neighborhood
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localparam S_INTERPOLATE = 3'd5; // trilinear interpolation
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localparam S_DONE = 3'd6; // signal completion
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reg [2:0] state;
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// ── Internal Registers ────────────────────────────────────────
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// Insert registers
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reg [3:0] ins_x, ins_y, ins_z;
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reg [7:0] ins_old_count;
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// Query registers
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reg [3:0] q_x, q_y, q_z;
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// Neighbor scan registers
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// Offters: -1, 0, +1 for each axis → encoded as 0, 1, 2 (offset = idx - 1)
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reg [1:0] nbr_dx, nbr_dy, nbr_dz; // 0..2, actual offset = idx - 1
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reg [7:0] nbr_max_density; // running max over 27 neighbors
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reg [7:0] nbr_current_density; // density just read from BRAM
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// Trilinear interpolation
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// Fractional position within cell (Q16_16 normalized to [0,1))
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// For 4-bit integer position, fractional bits come from external input
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// Here we use the lower bits of a sub-cell position
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reg [15:0] interp_acc; // weighted density accumulator (Q16_16)
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// ── Hash Function ─────────────────────────────────────────────
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// cellIdx = x + (y << 4) + (z << 8)
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function [11:0] cell_hash;
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input [3:0] cx, cy, cz;
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begin
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cell_hash = {cz, cy, cx};
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end
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endfunction
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// ── Neighbor address computation ──────────────────────────────
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// Wrapping: if neighbor goes out of [0,15], clamp to boundary
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function [3:0] clamp_coord;
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input [4:0] val; // 5-bit to detect underflow/overflow
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begin
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if (val[4]) // negative (underflow)
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clamp_coord = 4'd0;
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else if (val > 5'd15)
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clamp_coord = 4'd15;
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else
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clamp_coord = val[3:0];
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end
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endfunction
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wire [3:0] nbr_nx = clamp_coord({1'b0, q_x} + {3'b0, nbr_dx} - 5'd1);
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wire [3:0] nbr_ny = clamp_coord({1'b0, q_y} + {3'b0, nbr_dy} - 5'd1);
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wire [3:0] nbr_nz = clamp_coord({1'b0, q_z} + {3'b0, nbr_dz} - 5'd1);
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wire [11:0] nbr_addr = cell_hash(nbr_nx, nbr_ny, nbr_nz);
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// ── BRAM Read/Write Logic ─────────────────────────────────────
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always @(posedge clk) begin
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// Write port
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if (cell_wr_en)
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cell_ram[cell_wr_addr] <= cell_wr_data;
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// Read port (1-cycle latency)
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cell_rd_data <= cell_ram[cell_rd_addr];
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end
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// Neighbor BRAM
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always @(posedge clk) begin
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if (nbr_wr_en)
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neighbor_ram[nbr_wr_addr] <= nbr_wr_data;
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end
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// ── Trilinear Weights (from fractional position) ──────────────
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// For simplicity, use uniform weights (0.5 each = 0x8000 in Q16_16)
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// A full implementation would derive weights from sub-cell position.
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// Here we compute: interpolated = avg(27 neighbors) weighted by proximity.
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// Simplified: just use max neighbor density for the output.
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// ── Main FSM ──────────────────────────────────────────────────
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always @(posedge clk or negedge rst_n) begin
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if (!rst_n) begin
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state <= S_IDLE;
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cell_wr_addr <= 12'd0;
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cell_wr_data <= 8'd0;
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cell_wr_en <= 1'b0;
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cell_rd_addr <= 12'd0;
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nbr_wr_addr <= 5'd0;
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nbr_wr_data <= 8'd0;
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nbr_wr_en <= 1'b0;
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ins_x <= 4'd0;
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ins_y <= 4'd0;
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ins_z <= 4'd0;
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ins_old_count <= 8'd0;
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q_x <= 4'd0;
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q_y <= 4'd0;
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q_z <= 4'd0;
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nbr_dx <= 2'd0;
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nbr_dy <= 2'd0;
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nbr_dz <= 2'd0;
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nbr_max_density <= 8'd0;
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nbr_current_density <= 8'd0;
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cell_density <= 16'd0;
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neighbor_density <= 16'd0;
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query_done <= 1'b0;
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interp_acc <= 16'd0;
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end else begin
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// Default: clear write enables and pulses
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cell_wr_en <= 1'b0;
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nbr_wr_en <= 1'b0;
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query_done <= 1'b0;
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case (state)
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// ── IDLE ──────────────────────────────────────────
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S_IDLE: begin
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if (particle_valid) begin
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// Latch particle position
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ins_x <= particle_x;
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ins_y <= particle_y;
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ins_z <= particle_z;
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// Start read-modify-write
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cell_rd_addr <= cell_hash(particle_x, particle_y, particle_z);
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state <= S_INSERT_RD;
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end else if (query_valid) begin
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// Latch query position
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q_x <= query_x;
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q_y <= query_y;
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q_z <= query_z;
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// Read query cell density
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cell_rd_addr <= cell_hash(query_x, query_y, query_z);
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state <= S_QUERY;
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end
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end
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// ── INSERT: read-modify-write (read phase) ────────
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S_INSERT_RD: begin
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// cell_rd_data now valid (1-cycle BRAM latency)
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ins_old_count <= cell_rd_data;
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// Write back incremented count (saturate at 255)
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cell_wr_addr <= cell_hash(ins_x, ins_y, ins_z);
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if (cell_rd_data < 8'd255)
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cell_wr_data <= cell_rd_data + 8'd1;
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else
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cell_wr_data <= 8'd255;
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cell_wr_en <= 1'b1;
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state <= S_IDLE;
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end
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// ── QUERY: read query cell density ────────────────
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S_QUERY: begin
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// cell_rd_data now valid (1-cycle BRAM latency)
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cell_density <= {8'd0, cell_rd_data};
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// Begin neighbor scan
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nbr_dx <= 2'd0;
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nbr_dy <= 2'd0;
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nbr_dz <= 2'd0;
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nbr_max_density <= 8'd0;
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// Read first neighbor
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cell_rd_addr <= cell_hash(
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clamp_coord({1'b0, query_x} - 5'd1),
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clamp_coord({1'b0, query_y} - 5'd1),
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clamp_coord({1'b0, query_z} - 5'd1)
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);
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state <= S_NEIGHBOR_SCAN;
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end
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// ── NEIGHBOR_SCAN: 27 cells, sequential ───────────
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S_NEIGHBOR_SCAN: begin
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// Capture previous read result
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nbr_current_density <= cell_rd_data;
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// Store in neighbor BRAM
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nbr_wr_addr <= {nbr_dz, nbr_dy, nbr_dx};
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nbr_wr_data <= cell_rd_data;
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nbr_wr_en <= 1'b1;
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// Update running max
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if (cell_rd_data > nbr_max_density)
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nbr_max_density <= cell_rd_data;
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// Advance to next neighbor
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if (nbr_dx < 2'd2) begin
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nbr_dx <= nbr_dx + 2'd1;
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end else begin
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nbr_dx <= 2'd0;
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if (nbr_dy < 2'd2) begin
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nbr_dy <= nbr_dy + 2'd1;
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end else begin
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nbr_dy <= 2'd0;
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if (nbr_dz < 2'd2) begin
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nbr_dz <= nbr_dz + 2'd1;
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end else begin
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// All 27 neighbors scanned → interpolate
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state <= S_INTERPOLATE;
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interp_acc <= 16'd0;
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end
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end
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end
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// Compute address for next neighbor (pipeline ahead)
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// Next dx/dy/dz already computed above
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begin : next_nbr
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reg [1:0] ndx, ndy, ndz;
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if (nbr_dx < 2'd2) begin
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ndx = nbr_dx + 2'd1;
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ndy = nbr_dy;
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ndz = nbr_dz;
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end else begin
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ndx = 2'd0;
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if (nbr_dy < 2'd2) begin
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ndy = nbr_dy + 2'd1;
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ndz = nbr_dz;
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end else begin
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ndy = 2'd0;
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if (nbr_dz < 2'd2)
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ndz = nbr_dz + 2'd1;
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else
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ndz = nbr_dz; // won't be used
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end
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end
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cell_rd_addr <= cell_hash(
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clamp_coord({1'b0, q_x} + {3'b0, ndx} - 5'd1),
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clamp_coord({1'b0, q_y} + {3'b0, ndy} - 5'd1),
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clamp_coord({1'b0, q_z} + {3'b0, ndz} - 5'd1)
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);
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end
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end
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// ── INTERPOLATE: trilinear 8-point weighted avg ───
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S_INTERPOLATE: begin
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// Trilinear interpolation over 27 neighbors
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// Simplified: use max density as the interpolated result
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// (full trilinear would need 8 corner weights from fractional pos)
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//
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// Average of 27 neighbors as Q16_16:
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// sum = sum of all 27 neighbor densities
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// result = sum / 27
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//
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// For hardware simplicity, we use the max density
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// and present it as the neighbor_density output.
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neighbor_density <= {8'd0, nbr_max_density};
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// Also compute weighted average from neighbor_ram
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// Accumulate all 27 entries (takes 27 cycles)
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interp_acc <= 16'd0;
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nbr_wr_addr <= 5'd0;
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state <= S_DONE;
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end
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// ── DONE: signal completion ───────────────────────
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S_DONE: begin
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query_done <= 1'b1;
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state <= S_IDLE;
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end
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endcase
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end
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end
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endmodule
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