diff --git a/libraries/dsp/fft/src/vhdl/fft_pkg.vhd b/libraries/dsp/fft/src/vhdl/fft_pkg.vhd
index a177c9b2360167cb6ca9a00f118b3f452a61de4c..4f9f25c459d3701cb593baa455b649287b7609a9 100644
--- a/libraries/dsp/fft/src/vhdl/fft_pkg.vhd
+++ b/libraries/dsp/fft/src/vhdl/fft_pkg.vhd
@@ -69,7 +69,12 @@ package fft_pkg is
-- Check consistancy of the FFT parameters
function fft_r2_parameter_asserts(g_fft : t_fft) return boolean; -- the return value is void, because always true or abort due to failure
-
+
+ -- FFT input and output widths
+ function func_fft_in_scale_w(g_fft : t_fft) return natural;
+ function func_fft_raw_dat_w(g_fft : t_fft) return natural;
+ function func_fft_raw_fraction_w(g_fft : t_fft) return natural;
+
-- Definitions for fft slv array (an array can not have unconstraint elements, so choose sufficiently wide 32 bit slv elements)
subtype t_fft_slv_arr is t_slv_32_arr; -- use subtype to ease interfacing to existing types and to have central definition for rtwo components
constant c_fft_slv_w : natural := 32; -- match slv width of t_fft_slv_arr
@@ -106,7 +111,31 @@ package body fft_pkg is
assert g_fft.use_fft_shift=false report "fft_r2 : with use_separate there cannot be use_fft_shift for two real inputs" severity failure;
end if;
return true;
- end;
+ end;
+
+ -- Scale input data to MSbits of stage data, with g_fft.guard_w bits backoff if g_fft.guard_enable = true
+ function func_fft_in_scale_w(g_fft : t_fft) return natural is
+ constant c_in_scale_w : natural := g_fft.stage_dat_w - g_fft.in_dat_w - sel_a_b(g_fft.guard_enable, g_fft.guard_w, 0);
+ begin
+ return c_in_scale_w;
+ end func_fft_in_scale_w;
+
+ -- Raw output data width is equal to the internal data width of the FFT
+ function func_fft_raw_dat_w(g_fft : t_fft) return natural is
+ constant c_sepa_growth_w : natural := sel_a_b(g_fft.use_separate, 1, 0); -- add one bit for add sub growth in separate
+ constant c_raw_dat_w : natural := g_fft.stage_dat_w + c_sepa_growth_w;
+ begin
+ return c_raw_dat_w;
+ end func_fft_raw_dat_w;
+
+ -- Number of LSbits in the raw output data that represent the fraction bits in c_raw_dat_w.
+ function func_fft_raw_fraction_w(g_fft : t_fft) return natural is
+ constant c_raw_dat_w : natural := func_fft_raw_dat_w(g_fft);
+ constant c_raw_fraction_w : natural := c_raw_dat_w - g_fft.out_dat_w - g_fft.out_gain_w;
+ begin
+ return c_raw_fraction_w;
+ end func_fft_raw_fraction_w;
+
function to_fft_svec(n : integer) return std_logic_vector is
begin
diff --git a/libraries/dsp/fft/src/vhdl/fft_r2_par.vhd b/libraries/dsp/fft/src/vhdl/fft_r2_par.vhd
index 02bf10f3cdc378575e093c4651fad58d5891f3ff..aca22cb6ad028a06e9c358b338d56b84a5ac1fb6 100644
--- a/libraries/dsp/fft/src/vhdl/fft_r2_par.vhd
+++ b/libraries/dsp/fft/src/vhdl/fft_r2_par.vhd
@@ -127,15 +127,12 @@ architecture str of fft_r2_par is
constant c_pipeline_remove_lsb : natural := 1;
constant c_nof_stages : natural := ceil_log2(g_fft.nof_points);
- constant c_nof_bf_per_stage : natural := g_fft.nof_points/2;
- constant c_in_scale_w_tester : integer := g_fft.stage_dat_w - g_fft.in_dat_w - sel_a_b(g_fft.guard_enable, g_fft.guard_w, 0);
- constant c_in_scale_w : natural := sel_a_b(c_in_scale_w_tester > 0, c_in_scale_w_tester, 0); -- Only scale when in_dat_w is not too big.
-
- constant c_out_scale_w : integer := g_fft.stage_dat_w - g_fft.out_dat_w - g_fft.out_gain_w; -- Estimate number of LSBs to throw away when > 0 or insert when < 0
+ constant c_nof_bf_per_stage : natural := g_fft.nof_points/2;
+
+ constant c_in_scale_w : natural := func_fft_in_scale_w(g_fft);
+ constant c_raw_fraction_w : natural := func_fft_raw_fraction_w(g_fft);
+ constant c_raw_dat_w : natural := func_fft_raw_dat_w(g_fft);
- constant c_sepa_growth_w : natural := sel_a_b(g_fft.use_separate, 1, 0); -- add one bit for add sub growth in separate
- constant c_raw_dat_w : natural := g_fft.stage_dat_w + c_sepa_growth_w;
-
type t_stage_dat_arr is array (integer range <>) of std_logic_vector(g_fft.stage_dat_w-1 downto 0);
type t_stage_raw_arr is array (integer range <>) of std_logic_vector(c_raw_dat_w-1 downto 0);
type t_data_arr2 is array(c_nof_stages downto 0) of t_stage_dat_arr(g_fft.nof_points-1 downto 0);
@@ -158,6 +155,12 @@ architecture str of fft_r2_par is
signal fft_im_arr : t_stage_raw_arr(g_fft.nof_points-1 downto 0);
signal fft_val : std_logic;
+ -- debug signals to view parameters in Wave Window
+ signal dbg_g_g_fft : t_fft := g_fft;
+ signal dbg_c_in_scale_w : natural := c_in_scale_w;
+ signal dbg_c_raw_fraction_w : natural := c_raw_fraction_w;
+ signal dbg_c_raw_dat_w : natural := c_raw_dat_w;
+
begin
------------------------------------------------------------------------------
@@ -378,7 +381,7 @@ begin
u_requantize_re : entity common_lib.common_requantize
generic map (
g_representation => "SIGNED",
- g_lsb_w => c_out_scale_w + c_sepa_growth_w,
+ g_lsb_w => c_raw_fraction_w,
g_lsb_round => TRUE,
g_lsb_round_clip => FALSE,
g_msb_clip => FALSE,
@@ -398,7 +401,7 @@ begin
u_requantize_im : entity common_lib.common_requantize
generic map (
g_representation => "SIGNED",
- g_lsb_w => c_out_scale_w + c_sepa_growth_w,
+ g_lsb_w => c_raw_fraction_w,
g_lsb_round => TRUE,
g_lsb_round_clip => FALSE,
g_msb_clip => FALSE,
diff --git a/libraries/dsp/fft/src/vhdl/fft_r2_pipe.vhd b/libraries/dsp/fft/src/vhdl/fft_r2_pipe.vhd
index a121630cc5a7d4cfae4612e8131265005feea65d..fb54876255fc2dc4474ef12659c55ec7b8b3fd41 100644
--- a/libraries/dsp/fft/src/vhdl/fft_r2_pipe.vhd
+++ b/libraries/dsp/fft/src/vhdl/fft_r2_pipe.vhd
@@ -56,7 +56,19 @@
--
-- c0f0 c0f1 c0f2 ... c0f15 c1f0 c1f1 c1f2 ... c1f15 (c0f0 means channel 0, frequency bin 0)
--
---
+-- . Output subband widths:
+-- - out_quant_re/im : g_fft.out_dat_w bits (within c_32 word)
+-- - out_raw_re/im : c_raw_dat_w bits (within c_32 word)
+-- The out_quant carries subbands of g_fft.out_dat_w bits, so the
+-- c_raw_fraction_w fraction bits in c_raw_dat_w have been rounded.
+-- The out_raw carries subbands of c_raw_dat_w bits, that still have the
+-- c_raw_fraction_w fraction bits. The out_raw subbands are suitable for
+-- further weighting or alternative rounding.
+-- Note that c_raw_dat_w and c_raw_fraction_w depend on g_fft.use_separate.
+-- For real input data FFT there is one fraction bit more than for complex
+-- input FFT, due to the adder stage in the separate function.
+-- Both out_quant and out_raw use FFT out_val, so they have the same timing.
+--
library ieee, common_lib, rTwoSDF_lib;
use IEEE.std_logic_1164.all;
@@ -88,7 +100,7 @@ end entity fft_r2_pipe;
architecture str of fft_r2_pipe is
- constant c_pipeline_remove_lsb : natural := 0;
+ constant c_pipeline_remove_lsb : natural := 1; -- to easy timing closure
constant c_switch_en : boolean := g_fft.use_separate; -- default do apply switch/unswitch per real input to mitigate quantization crosstalk
constant c_switch_sz_w : natural := ceil_log2(g_fft.nof_points) + g_fft.nof_chan;
@@ -96,11 +108,12 @@ architecture str of fft_r2_pipe is
constant c_switch_seed1 : STD_LOGIC_VECTOR(c_fft_lfsr_len-1 DOWNTO 0) := fft_switch_new_seed(c_fft_switch_seed1, g_instance_index);
constant c_switch_seed2 : STD_LOGIC_VECTOR(c_fft_lfsr_len-1 DOWNTO 0) := fft_switch_new_seed(c_fft_switch_seed2, g_instance_index);
constant c_nof_stages : natural := ceil_log2(g_fft.nof_points);
- constant c_stage_offset : natural := true_log2(g_fft.wb_factor); -- Stage offset is required for twiddle generation in wideband fft
- constant c_in_scale_w : natural := g_fft.stage_dat_w - g_fft.in_dat_w - sel_a_b(g_fft.guard_enable, g_fft.guard_w, 0);
- constant c_out_scale_w : integer := g_fft.stage_dat_w - g_fft.out_dat_w - g_fft.out_gain_w; -- Estimate number of LSBs to throw throw away when > 0 or insert when < 0
- constant c_sepa_growth_w : natural := sel_a_b(g_fft.use_separate, 1, 0); -- add one bit for add sub growth in separate
- constant c_raw_dat_w : natural := g_fft.stage_dat_w + c_sepa_growth_w;
+ constant c_stage_offset : natural := true_log2(g_fft.wb_factor); -- Stage offset is required for twiddle generation in wideband fft
+
+ constant c_in_scale_w : natural := func_fft_in_scale_w(g_fft);
+ constant c_raw_fraction_w : natural := func_fft_raw_fraction_w(g_fft);
+ constant c_raw_dat_w : natural := func_fft_raw_dat_w(g_fft);
+
constant c_unswitch_dat_w : natural := c_raw_dat_w; -- no need for extra bit, because most negative value cannot occur in FFT output
-- number the stage instances from c_nof_stages:1
@@ -134,8 +147,7 @@ architecture str of fft_r2_pipe is
-- debug signals to view parameters in Wave Window
signal dbg_g_g_fft : t_fft := g_fft;
signal dbg_c_in_scale_w : natural := c_in_scale_w;
- signal dbg_c_out_scale_w : integer := c_out_scale_w;
- signal dbg_c_sepa_growth_w : natural := c_sepa_growth_w;
+ signal dbg_c_raw_fraction_w : natural := c_raw_fraction_w;
signal dbg_c_raw_dat_w : natural := c_raw_dat_w;
begin
@@ -286,7 +298,7 @@ begin
u_requantize_re : entity common_lib.common_requantize
generic map (
g_representation => "SIGNED",
- g_lsb_w => c_out_scale_w + c_sepa_growth_w,
+ g_lsb_w => c_raw_fraction_w,
g_lsb_round => TRUE,
g_lsb_round_clip => FALSE,
g_msb_clip => FALSE,
@@ -306,7 +318,7 @@ begin
u_requantize_im : entity common_lib.common_requantize
generic map (
g_representation => "SIGNED",
- g_lsb_w => c_out_scale_w + c_sepa_growth_w,
+ g_lsb_w => c_raw_fraction_w,
g_lsb_round => TRUE,
g_lsb_round_clip => FALSE,
g_msb_clip => FALSE,
@@ -336,9 +348,10 @@ begin
------------------------------------------------------------------------------
-- Pipelined FFT raw output register
- -- . Pipeline out_raw_* to align with out_quant_*, so they can share out_val
------------------------------------------------------------------------------
+ -- . Pipeline out_raw to align with out_quant, so they can share
+ -- out_val.
u_out_raw_re : entity common_lib.common_pipeline
generic map (
g_representation => "SIGNED",
diff --git a/libraries/dsp/fft/src/vhdl/fft_r2_wide.vhd b/libraries/dsp/fft/src/vhdl/fft_r2_wide.vhd
index 0a2be83321af8634aee38c7b1ab681930c40db62..209ac150ba20fbde3b23005f8a1eaf9716fc53fd 100644
--- a/libraries/dsp/fft/src/vhdl/fft_r2_wide.vhd
+++ b/libraries/dsp/fft/src/vhdl/fft_r2_wide.vhd
@@ -148,12 +148,9 @@ architecture rtl of fft_r2_wide is
constant c_fft_r2_pipe_arr : t_fft_arr(g_fft.wb_factor-1 downto 0) := func_create_generic_for_pipe_fft(g_fft);
constant c_fft_r2_par : t_fft := func_create_generic_for_par_fft(g_fft);
- constant c_in_scale_w : natural := g_fft.stage_dat_w - g_fft.in_dat_w - sel_a_b(g_fft.guard_enable, g_fft.guard_w, 0);
-
- constant c_out_scale_w : integer := c_fft_r2_par.out_dat_w - g_fft.out_dat_w - g_fft.out_gain_w; -- Estimate number of LSBs to throw away when > 0 or insert when < 0
-
- constant c_sepa_growth_w : natural := sel_a_b(g_fft.use_separate, 1, 0); -- add one bit for add sub growth in separate
- constant c_raw_dat_w : natural := g_fft.stage_dat_w + c_sepa_growth_w;
+ constant c_in_scale_w : natural := func_fft_in_scale_w(g_fft);
+ constant c_raw_fraction_w : natural := func_fft_raw_fraction_w(g_fft);
+ constant c_raw_dat_w : natural := func_fft_raw_dat_w(g_fft);
-- g_fft.wb_factor = 1
signal fft_pipe_out_re : std_logic_vector(g_fft.out_dat_w-1 downto 0);
@@ -182,8 +179,7 @@ architecture rtl of fft_r2_wide is
-- debug signals to view parameters in Wave Window
signal dbg_g_g_fft : t_fft := g_fft;
signal dbg_c_in_scale_w : natural := c_in_scale_w;
- signal dbg_c_out_scale_w : integer := c_out_scale_w;
- signal dbg_c_sepa_growth_w : natural := c_sepa_growth_w;
+ signal dbg_c_raw_fraction_w : natural := c_raw_fraction_w;
signal dbg_c_raw_dat_w : natural := c_raw_dat_w;
begin
@@ -328,7 +324,7 @@ begin
u_requantize_output_re : entity common_lib.common_requantize
generic map (
g_representation => "SIGNED",
- g_lsb_w => c_out_scale_w + c_sepa_growth_w,
+ g_lsb_w => c_raw_fraction_w,
g_lsb_round => TRUE,
g_lsb_round_clip => FALSE,
g_msb_clip => FALSE,
@@ -348,7 +344,7 @@ begin
u_requantize_output_im : entity common_lib.common_requantize
generic map (
g_representation => "SIGNED",
- g_lsb_w => c_out_scale_w + c_sepa_growth_w,
+ g_lsb_w => c_raw_fraction_w,
g_lsb_round => TRUE,
g_lsb_round_clip => FALSE,
g_msb_clip => FALSE,