sha_mainloop.sv

`default_nettype none
`timescale 1 ns / 10 ps

module sha_mainloop	#(parameter PADDED_SIZE = 512)
					(input logic [PADDED_SIZE-1:0] padded,
					input logic clk, rst,
					output logic [255:0] hashed,
					output logic done);

	function [31:0] K;
		input [6:0] x;
		K = k[2047-x*32 -: 32];
	endfunction

	function automatic [31:0] W;
		input [6:0] x;
		input [6:0] y;
		if(^x === 1'bX) W = 32'h777;
		else W = (x<16) ? padded[((PADDED_SIZE-1-y*512)-x*32) -: 32] : rho1(W(x-2, y)) + W(x-7, y) + rho0(W(x-15, y)) + W(x-16, y);
	endfunction

	function automatic [31:0] rho0;
		input [31:0] x;
		if(^x === 1'bX) rho0 = 32'h888;
		else rho0 = {x[6:0],x[31:7]} ^ {x[17:0],x[31:18]} ^ (x >> 3);
	endfunction

	function automatic [31:0] rho1;
		input [31:0] x;
		if(^x === 1'bX) rho1 = 32'h888;
		else rho1 = {x[16:0],x[31:17]} ^ {x[18:0],x[31:19]} ^ (x >> 10);
	endfunction

	function [31:0] ch;
		input [31:0] x,y,z;
		if(^x === 1'bX) ch = 32'h888;
		else ch = (x & y) ^ (~x & z);
	endfunction

	function [31:0] maj;
		input [31:0] x,y,z;
		if(^x === 1'bX) maj = 32'h888;
		else maj = (x & y) ^ (x & z) ^ (y & z);
	endfunction

	function [31:0] sum0;
		input [31:0] x;
		if(^x === 1'bX) sum0 = 32'h888;
		else sum0 = {x[1:0],x[31:2]} ^ {x[12:0],x[31:13]} ^ {x[21:0],x[31:22]};
	endfunction

	function [31:0] sum1;
		input [31:0] x;
		if(^x === 1'bX) sum1 = 32'h888;
		else sum1 = {x[5:0],x[31:6]} ^ {x[10:0],x[31:11]} ^ {x[24:0],x[31:25]};
	endfunction

	logic [255:0] initial_hashes = {32'h6a09e667, 32'hbb67ae85, 32'h3c6ef372, 32'ha54ff53a, 32'h510e527f, 32'h9b05688c, 32'h1f83d9ab, 32'h5be0cd19};
	
	logic [2047:0] k = {32'h428a2f98, 32'h71374491, 32'hb5c0fbcf, 32'he9b5dba5, 32'h3956c25b, 32'h59f111f1, 32'h923f82a4, 32'hab1c5ed5, 32'hd807aa98, 32'h12835b01, 32'h243185be, 32'h550c7dc3, 32'h72be5d74, 32'h80deb1fe, 32'h9bdc06a7, 32'hc19bf174, 32'he49b69c1, 32'hefbe4786, 32'h0fc19dc6, 32'h240ca1cc, 32'h2de92c6f, 32'h4a7484aa, 32'h5cb0a9dc, 32'h76f988da, 32'h983e5152, 32'ha831c66d, 32'hb00327c8, 32'hbf597fc7, 32'hc6e00bf3, 32'hd5a79147, 32'h06ca6351, 32'h14292967, 32'h27b70a85, 32'h2e1b2138, 32'h4d2c6dfc, 32'h53380d13, 32'h650a7354, 32'h766a0abb, 32'h81c2c92e, 32'h92722c85, 32'ha2bfe8a1, 32'ha81a664b, 32'hc24b8b70, 32'hc76c51a3, 32'hd192e819, 32'hd6990624, 32'hf40e3585, 32'h106aa070, 32'h19a4c116, 32'h1e376c08, 32'h2748774c, 32'h34b0bcb5, 32'h391c0cb3, 32'h4ed8aa4a, 32'h5b9cca4f, 32'h682e6ff3, 32'h748f82ee, 32'h78a5636f, 32'h84c87814, 32'h8cc70208, 32'h90befffa, 32'ha4506ceb, 32'hbef9a3f7, 32'hc67178f2};

	logic [31:0] a, b, c, d, e, f, g, h, t1, t2;
	logic [31:0] h1, h2, h3, h4, h5, h6, h7, h8;

	logic [6:0] j;
	logic [6:0] i;

	localparam N = PADDED_SIZE/512; // number of blocks
	
	logic [31:0] ch_efg, maj_abc, sum0_a, sum1_e, kj, wj;

	always_comb begin
		ch_efg = ch(e,f,g);
		maj_abc = maj(a,b,c);
		sum0_a = sum0(a);
		sum1_e = sum1(e);
		wj = W(j, i);
		kj = K(j);
	end

	always @(negedge clk) begin
		// t1 <= h + sum1(e) + ch(e,f,g) + K(j) + W(j);
		// t2 <= sum0(a) + maj(a,b,c);
		t1 <= (h + sum1_e + ch_efg + kj + wj)%4294967296;
		t2 <= (sum0_a + maj_abc)%4294967296;
	end

	always @(posedge clk or posedge rst) begin
		if(rst) begin
			i 	<= 1'b0;
			j 	<= 1'bX;
			h1 	<= 32'h6a09e667;
			h2 	<= 32'hbb67ae85;
			h3 	<= 32'h3c6ef372;
			h4 	<= 32'ha54ff53a;
			h5 	<= 32'h510e527f;
			h6 	<= 32'h9b05688c;
			h7 	<= 32'h1f83d9ab;
			h8 	<= 32'h5be0cd19;
		end
		else if (^j === 1'bX && ^i !== 1'bX) begin
			a <= h1;
			b <= h2;
			c <= h3;
			d <= h4;
			e <= h5;
			f <= h6;
			g <= h7;
			h <= h8;
			j <= 1'd0;
		end
		else if (j < 64) begin
			h <= g;
			g <= f;
			f <= e;
			e <= (d+t1)%4294967296;
			d <= c;
			c <= b;
			b <= a;
			a <= (t1+t2)%4294967296;
			j <= j+1;
		end
		else if (j == 64) begin
			h1 <= a + h1;
			h2 <= b + h2;
			h3 <= c + h3;
			h4 <= d + h4;
			h5 <= e + h5;
			h6 <= f + h6;
			h7 <= g + h7;
			h8 <= h + h8;
			j <= 1'bX;
			if (i<N-1) i <= i+1;
			else begin
				i <= 1'bX;
				done <= 1'b1;
			end
		end
	end

	assign hashed = {h1, h2, h3, h4, h5, h6, h7, h8};
endmodule