platform/wavelet3d: implement int->float conversion

2 files changed, 103 insertions, 45 deletions

diff --git a/platform/wavelet3d/gfx_fpint_lane.sv b/platform/wavelet3d/gfx_fpint_lane.sv
index 0010f06..63d56e2 100644
--- a/platform/wavelet3d/gfx_fpint_lane.sv
+++ b/platform/wavelet3d/gfx_fpint_lane.sv
@@ -10,10 +10,12 @@ module gfx_fpint_lane
 	                  float_a_1,
 	                  int_hi_a_1,
 	                  int_lo_a_1,
-	                  zero_flags_a_1,
+	                  zero_flags_1,
 	                  zero_b_1,
 	                  copy_flags_2,
+	                  int_signed_4,
 	                  copy_flags_5,
+	                  int_operand_5,
 	                  enable_norm_6,
 	                  copy_flags_10,
 	                  copy_flags_11,
@@ -25,9 +27,10 @@ module gfx_fpint_lane
 
 	import gfx::*;
 
-	/* Notas de implementación para floating-point.
+	/* Notas de implementación para floating-point
 	*
 	* === PRODUCTO ===
+	*
 	* Queremos calcular q = a * b.
 	 *
 	 * Donde a = (-1)^s * 1.m * 2^f,
@@ -55,10 +58,19 @@ module gfx_fpint_lane
 	 * En el caso de una resta, el exponente normalizado puede ser mucho más
 	 * pequeño que cualquiera de los exponentes de entrada. Necesitamos
 	 * entonces de lǵoica CLZ (count leading zeros) para renormalizar.
+	 *
+	 *
+	 * === CONVERSIÓN INTEGER->FP ===
+	 *
+	 * Esto simplemente usa el mismo datapath de fadd, con el abs del entero
+	 * como entrada como entrada de clz. El exponente de referencia se fija
+	 * en 30 (aludiendo al segundo msb de un entero de 32 bits). A partir de
+	 * ese punto es idéntico a un fadd, las etapas de clz se encargan de ajustar
+	 * el exponente.
 	 */
 
 	logic exp_step, guard_0, guard_1, guard_2, guard_3, guard_4, guard_5, guard_10,
-	      lo_msb, lo_reduce, overflow_0, overflow_1, overflow_10, overflow_12,
+	      int_sign, lo_msb, lo_reduce, overflow_0, overflow_1, overflow_10, overflow_12,
 	      round_0, round_1, round_2, round_3, round_4, round_5, round_10, sign_0,
 	      sign_10, sign_11, sign_12, slow_1, slow_2, slow_3, slow_4, slow_5, slow_10,
 	      slow_11, slow_12, slow_in_1, slow_in_next, slow_out, sticky_1, sticky_2,
@@ -71,7 +83,7 @@ module gfx_fpint_lane
 	float_class a_class_0, a_class_1, b_class_0, b_class_1,
 	            max_class_2, max_class_3, min_class_2, min_class_3, min_class_4;
 
-	word clz_in, product_hi, product_lo;
+	word add_sub, clz_in, normalized, product_hi, product_lo;
 	dword product;
 	float_exp exp, exp_11, exp_10, exp_12, exp_delta;
 	float_mant mant_10, mant_11, mant_12;
@@ -81,15 +93,13 @@ module gfx_fpint_lane
 	typedef logic[$bits(float_mant_full) + 1:0] extended_mant;
 	localparam bit[$clog2($bits(extended_mant)):0] MAX_SHIFT = 1 << $clog2($bits(extended_mant));
 
-	localparam int SHIFT_WIDTH     = {{($bits(int) - $bits(MAX_SHIFT)){1'b0}}, MAX_SHIFT};
-	localparam int CLZ_EXTEND_BITS = $bits(float_exp) - $bits(clz_shift) + 1;
-
-	typedef logic[$bits(float_mant_full) + 2:0] mant_sum;
-
-	mant_sum add_sub, normalized;
 	extended_mant max_mant, min_mant, sticky_mask;
 	logic[$clog2(MAX_SHIFT):0] clz_shift, exp_shift;
 
+	localparam int INT_SHIFT_REF   = $bits(word) - 2;
+	localparam int SHIFT_WIDTH     = {{($bits(int) - $bits(MAX_SHIFT)){1'b0}}, MAX_SHIFT};
+	localparam int CLZ_EXTEND_BITS = $bits(float_exp) - $bits(clz_shift) + 1;
+
 	struct packed
 	{
 		float    max;
@@ -98,7 +108,7 @@ module gfx_fpint_lane
 		         slow,
 		         sticky,
 		         zero;
-		mant_sum add_sub;
+		word     add_sub;
 	} clz_hold[FADD_CLZ_STAGES], clz_hold_out;
 
 	gfx_clz #($bits(word)) clz
@@ -112,18 +122,22 @@ module gfx_fpint_lane
 		extend_min_max = {~in_class.exp_min, in.mant, 2'b00};
 	endfunction
 
+	function word fp_add_sub_arg(extended_mant arg);
+		fp_add_sub_arg = {1'b0, arg, {($bits(fp_add_sub_arg) - $bits(arg) - 1){1'b0}}};
+	endfunction
+
 	assign lo_msb = lo[$bits(lo) - 1];
 	assign slow_out = &exp_12 || slow_12 || overflow_12;
 	assign exp_delta = max_2.exp - min_2.exp;
 	assign lo_reduce = |lo[$bits(lo) - 2:0];
-	assign normalized = add_sub << clz_shift;
+	assign normalized = clz_hold_out.add_sub << clz_shift;
 	assign clz_hold_out = clz_hold[FADD_CLZ_STAGES - 1];
 	assign slow_in_next = is_float_special(a_class_0) | is_float_special(b_class_0);
 	assign {product_hi, product_lo} = product;
 	assign {hi, guard_0, round_0, lo} = product[2 * $bits(float_mant_full) - 1:0];
 
 	always_comb begin
-		clz_in = {add_sub, {($bits(clz_in) - $bits(add_sub)){1'b0}}};
+		clz_in = add_sub;
 		if (~enable_norm_6)
 			clz_in[$bits(clz_in) - 1:$bits(clz_in) - 2] = 2'b01;
 	end
@@ -136,8 +150,8 @@ module gfx_fpint_lane
 		a_mul <= a;
 		b_mul <= b;
 
-		/* Nótese que el orden es sign-exp-mant. Esto coloca el 1. implícito
-		 * en la posición correcta para multiplicar mantisas.
+		/* Nótese que el orden es sign-exp-mant. Esto coloca el '1.' implícito
+		 * en la posición correcta para multiplicar las mantisas.
 		 */
 		if (mul_float_m1) begin
 			a_mul.exp <= 1;
@@ -146,10 +160,10 @@ module gfx_fpint_lane
 			b_mul.sign <= 0;
 		end
 
-		// Genera un nop junto a lo anterior
 		if (unit_b_m1) begin
 			b_mul.exp <= 0;
 			b_mul.mant <= 1;
+			b_mul.sign <= 0;
 		end
 
 		// Stage 0: multiplicación de fp o enteros
@@ -163,9 +177,6 @@ module gfx_fpint_lane
 
 		// Stage 1: normalización
 
-		slow_in_1 <= slow_in_next;
-		overflow_1 <= 0;
-
 		if (float_a_1) begin
 			slow_1 <= slow_in_next | (overflow_0 & ~a_class_0.exp_min & ~a_class_1.exp_min);
 			zero_1 <= a_class_0.exp_min | b_class_0.exp_min;
@@ -174,7 +185,9 @@ module gfx_fpint_lane
 			zero_1 <= 0;
 		end
 
+		overflow_1 <= 0;
 		a_add.sign <= sign_0;
+
 		if (hi[$bits(hi) - 1]) begin
 			guard_1 <= guard_0;
 			round_1 <= round_0;
@@ -203,8 +216,12 @@ module gfx_fpint_lane
 		endcase
 
 		a_class_1 <= a_class_0;
-		if (zero_flags_a_1)
+		slow_in_1 <= slow_in_next;
+
+		if (zero_flags_1) begin
 			a_class_1 <= classify_float(0);
+			slow_in_1 <= 0;
+		end
 
 		if (zero_b_1) begin
 			b_add <= 0;
@@ -264,9 +281,8 @@ module gfx_fpint_lane
 		if (exp_delta > {{($bits(exp_delta) - $bits(MAX_SHIFT)){1'b0}}, MAX_SHIFT})
 			exp_shift <= MAX_SHIFT;
 
-		// Stage 4: shifts
+		// Stage 4: shifts y abs(max) para enteros con signo
 
-		max_4 <= max_3;
 		min_4 <= min_3;
 		slow_4 <= slow_3;
 		zero_4 <= zero_3;
@@ -279,7 +295,13 @@ module gfx_fpint_lane
 		min_mant <= extend_min_max(min_3, min_class_3) >> exp_shift;
 		sticky_mask <= {($bits(min_mant)){1'b1}} << exp_shift;
 
-		// Stage 5: suma/resta y sticky
+		max_4 <= max_3;
+		int_sign <= max_3[$bits(max_3) - 1];
+
+		if (int_signed_4 & max_3[$bits(max_3) - 1])
+			max_4 <= -max_3;
+
+		// Stage 5: suma de mantisas
 
 		max_5 <= max_4;
 		slow_5 <= slow_4;
@@ -287,15 +309,22 @@ module gfx_fpint_lane
 		guard_5 <= guard_4;
 		round_5 <= round_4;
 
+		if (int_operand_5) begin
+			max_5.exp <= FLOAT_EXP_BIAS + INT_SHIFT_REF[$bits(float_exp) - 1:0];
+			max_5.sign <= int_sign;
+		end
+
 		if (copy_flags_5)
 			sticky_5 <= sticky_4;
 		else
 			sticky_5 <= |(extend_min_max(min_4, min_class_4) & ~sticky_mask);
 
-		if (max_4.sign ^ min_4.sign)
-			add_sub <= {1'b0, max_mant - min_mant};
+		if (int_operand_5)
+			add_sub <= max_4;
+		else if (max_4.sign ^ min_4.sign)
+			add_sub <= fp_add_sub_arg(max_mant) - fp_add_sub_arg(min_mant);
 		else
-			add_sub <= {1'b0, max_mant} + {1'b0, min_mant};
+			add_sub <= fp_add_sub_arg(max_mant) + fp_add_sub_arg(min_mant);
 
 		// Stages 6-9: clz
 
diff --git a/platform/wavelet3d/main.cpp b/platform/wavelet3d/main.cpp
index 1bffb68..037aee4 100644
--- a/platform/wavelet3d/main.cpp
+++ b/platform/wavelet3d/main.cpp
@@ -23,18 +23,41 @@ int main(int argc, char **argv)
 
 	Py_Initialize();
 
-	float a, b;
+	float q;
+	int a, b;
+	const char *op = "int->fp";
+
 	std::cin >> a >> b;
 
+	// int->fp
+	top.mul_float_m1 = 0;
+	top.unit_b_m1 = 1;
+	top.float_a_1 = 0;
+	top.int_hi_a_1 = 0;
+	top.int_lo_a_1 = 1;
+	top.zero_flags_1 = 1;
+	top.zero_b_1 = 1;
+	top.copy_flags_2 = 0;
+	top.int_signed_4 = 1;
+	top.int_operand_5 = 1;
+	top.copy_flags_5 = 1;
+	top.enable_norm_6 = 1;
+	top.copy_flags_10 = 0;
+	top.copy_flags_11 = 0;
+	top.enable_round_11 = 1;
+	top.encode_special_13 = 1;
+
 	// mul int
 	//top.mul_float_m1 = 0;
 	//top.unit_b_m1 = 0;
 	//top.float_a_1 = 0;
 	//top.int_hi_a_1 = 0;
 	//top.int_lo_a_1 = 1;
-	//top.zero_flags_a_1 = 1;
+	//top.zero_flags_1 = 1;
 	//top.zero_b_1 = 1;
 	//top.copy_flags_2 = 1;
+	//top.int_signed_4 = 0;
+	//top.int_operand_5 = 0;
 	//top.copy_flags_5 = 1;
 	//top.enable_norm_6 = 0;
 	//top.copy_flags_10 = 1;
@@ -48,10 +71,12 @@ int main(int argc, char **argv)
 	//top.float_a_1 = 1;
 	//top.int_hi_a_1 = 0;
 	//top.int_lo_a_1 = 0;
-	//top.zero_flags_a_1 = 0;
+	//top.zero_flags_1 = 0;
 	//top.zero_b_1 = 1;
 	//top.copy_flags_2 = 1;
 	//top.copy_flags_5 = 1;
+	//top.int_signed_4 = 0;
+	//top.int_operand_5 = 0;
 	//top.enable_norm_6 = 1;
 	//top.copy_flags_10 = 1;
 	//top.copy_flags_11 = 1;
@@ -59,20 +84,22 @@ int main(int argc, char **argv)
 	//top.encode_special_13 = 1;
 
 	// suma/resta
-	top.mul_float_m1 = 0;
-	top.unit_b_m1 = 1;
-	top.float_a_1 = 0;
-	top.int_hi_a_1 = 0;
-	top.int_lo_a_1 = 1;
-	top.zero_flags_a_1 = 0;
-	top.zero_b_1 = 0;
-	top.copy_flags_2 = 0;
-	top.copy_flags_5 = 0;
-	top.enable_norm_6 = 1;
-	top.copy_flags_10 = 0;
-	top.copy_flags_11 = 0;
-	top.enable_round_11 = 1;
-	top.encode_special_13 = 1;
+	//top.mul_float_m1 = 0;
+	//top.unit_b_m1 = 1;
+	//top.float_a_1 = 0;
+	//top.int_hi_a_1 = 0;
+	//top.int_lo_a_1 = 1;
+	//top.zero_flags_1 = 0;
+	//top.zero_b_1 = 0;
+	//top.copy_flags_2 = 0;
+	//top.copy_flags_5 = 0;
+	//top.int_signed_4 = 0;
+	//top.int_operand_5 = 0;
+	//top.enable_norm_6 = 1;
+	//top.copy_flags_10 = 0;
+	//top.copy_flags_11 = 0;
+	//top.enable_round_11 = 1;
+	//top.encode_special_13 = 1;
 
 	top.a = *reinterpret_cast<unsigned*>(&a);
 	top.b = *reinterpret_cast<unsigned*>(&b);
@@ -85,8 +112,10 @@ int main(int argc, char **argv)
 		top.eval();
 	}
 
-	unsigned q = top.q;
-	std::cout << a << " * " << b << " = " << *reinterpret_cast<decltype(a)*>(&q) << '\n';
+	unsigned q_bits = top.q;
+	q = *reinterpret_cast<decltype(q)*>(&q_bits);
+
+	std::cout << a << ' ' << op << ' ' << b << " = " << q << '\n';
 
 	bool failed = Py_FinalizeEx() < 0;