From 1649713a0ad79684da5ca2152a12c1bc47f41995 Mon Sep 17 00:00:00 2001
From: Eric Kooistra <kooistra@astron.nl>
Date: Fri, 8 Apr 2022 13:53:09 +0200
Subject: [PATCH] Support g_round_even. Default g_round_even = true.
---
libraries/dsp/rTwoSDF/src/vhdl/rTwoSDF.vhd | 8 ++-
.../dsp/rTwoSDF/src/vhdl/rTwoSDFStage.vhd | 14 +++--
libraries/dsp/rTwoSDF/src/vhdl/rTwoWMul.vhd | 53 +++++++++++++++----
libraries/dsp/rTwoSDF/tb/vhdl/tb_rTwoSDF.vhd | 3 +-
4 files changed, 59 insertions(+), 19 deletions(-)
diff --git a/libraries/dsp/rTwoSDF/src/vhdl/rTwoSDF.vhd b/libraries/dsp/rTwoSDF/src/vhdl/rTwoSDF.vhd
index 0674560603..feaaa25f8c 100644
--- a/libraries/dsp/rTwoSDF/src/vhdl/rTwoSDF.vhd
+++ b/libraries/dsp/rTwoSDF/src/vhdl/rTwoSDF.vhd
@@ -43,6 +43,7 @@ entity rTwoSDF is
g_stage_dat_w : natural := 18; -- number of bits used between the stages
g_guard_w : natural := 2; -- guard bits are used to avoid overflow in single FFT stage.
g_nof_points : natural := 1024; -- N point FFT
+ g_round_even : boolean := true;
-- generics for rTwoSDFStage
g_pipeline : t_fft_pipeline := c_fft_pipeline
);
@@ -104,6 +105,7 @@ begin
g_stage_offset => c_stage_offset,
g_twiddle_offset => c_twiddle_offset,
g_scale_enable => sel_a_b(stage <= g_guard_w, FALSE, TRUE), -- On average all stages have a gain factor of 2 therefore each stage needs to round 1 bit except for the last g_guard_w nof stages due to the input c_in_scale_w
+ g_round_even => g_round_even,
g_pipeline => g_pipeline
)
port map (
@@ -157,7 +159,8 @@ begin
g_representation => "SIGNED",
g_lsb_w => c_out_scale_w,
g_lsb_round => TRUE,
- g_lsb_round_clip => FALSE,
+ g_lsb_round_clip => FALSE,
+ g_lsb_round_even => g_round_even,
g_msb_clip => FALSE,
g_msb_clip_symmetric => FALSE,
g_pipeline_remove_lsb => 0,
@@ -179,7 +182,8 @@ begin
g_lsb_w => c_out_scale_w,
g_lsb_round => TRUE,
g_lsb_round_clip => FALSE,
- g_msb_clip => FALSE,
+ g_lsb_round_even => g_round_even,
+ g_msb_clip => FALSE,
g_msb_clip_symmetric => FALSE,
g_pipeline_remove_lsb => 0,
g_pipeline_remove_msb => 0,
diff --git a/libraries/dsp/rTwoSDF/src/vhdl/rTwoSDFStage.vhd b/libraries/dsp/rTwoSDF/src/vhdl/rTwoSDFStage.vhd
index 8f40621d13..389aca4cd7 100644
--- a/libraries/dsp/rTwoSDF/src/vhdl/rTwoSDFStage.vhd
+++ b/libraries/dsp/rTwoSDF/src/vhdl/rTwoSDFStage.vhd
@@ -31,7 +31,8 @@ entity rTwoSDFStage is
g_stage : natural := 8;
g_stage_offset : natural := 0; -- The Stage offset: 0 for normal FFT. Other than 0 in wideband FFT
g_twiddle_offset : natural := 0; -- The twiddle offset: 0 for normal FFT. Other than 0 in wideband FFT
- g_scale_enable : boolean := TRUE; --
+ g_scale_enable : boolean := TRUE;
+ g_round_even : boolean := TRUE;
g_pipeline : t_fft_pipeline := c_fft_pipeline -- internal pipeline settings
);
port (
@@ -146,8 +147,9 @@ begin
------------------------------------------------------------------------------
u_TwiddleMult: entity work.rTwoWMul
generic map (
- g_stage => g_stage,
- g_lat => g_pipeline.mul_lat
+ g_stage => g_stage,
+ g_round_even => g_round_even,
+ g_lat => g_pipeline.mul_lat
)
port map (
clk => clk,
@@ -171,7 +173,8 @@ begin
g_representation => "SIGNED",
g_lsb_w => c_r2_stage_bit_growth,
g_lsb_round => TRUE,
- g_lsb_round_clip => FALSE,
+ g_lsb_round_clip => FALSE,
+ g_lsb_round_even => g_round_even,
g_msb_clip => FALSE,
g_msb_clip_symmetric => FALSE,
g_pipeline_remove_lsb => 0,
@@ -193,7 +196,8 @@ begin
g_lsb_w => c_r2_stage_bit_growth,
g_lsb_round => TRUE,
g_lsb_round_clip => FALSE,
- g_msb_clip => FALSE,
+ g_lsb_round_even => g_round_even,
+ g_msb_clip => FALSE,
g_msb_clip_symmetric => FALSE,
g_pipeline_remove_lsb => 0,
g_pipeline_remove_msb => 0,
diff --git a/libraries/dsp/rTwoSDF/src/vhdl/rTwoWMul.vhd b/libraries/dsp/rTwoSDF/src/vhdl/rTwoWMul.vhd
index ead344fece..a508eda63d 100644
--- a/libraries/dsp/rTwoSDF/src/vhdl/rTwoWMul.vhd
+++ b/libraries/dsp/rTwoSDF/src/vhdl/rTwoWMul.vhd
@@ -29,6 +29,7 @@ entity rTwoWMul is
generic (
g_technology : NATURAL := c_tech_select_default;
g_stage : natural := 1;
+ g_round_even : boolean := true;
g_lat : natural := 3+1 -- 3 for mult, 1 for round
);
port (
@@ -184,17 +185,47 @@ begin
gen_sround : if c_use_truncate=false GENERATE
- -- Use resize_svec(s_round()) instead of truncate_and_resize_svec() to have symmetrical rounding around 0
- -- Rounding takes logic due to adding 0.5 therefore need to use c_round_lat=1 to achieve timing
- gen_comb : if c_round_lat=0 generate
- ASSERT false REPORT "rTwoWMul: can probably not achieve timing for sround without pipeline" SEVERITY FAILURE;
- round_re <= RESIZE_SVEC(s_round(product_re, c_round_w), c_out_dat_w);
- round_im <= RESIZE_SVEC(s_round(product_im, c_round_w), c_out_dat_w);
- end generate;
- gen_reg : if c_round_lat=1 generate
- round_re <= RESIZE_SVEC(s_round(product_re, c_round_w), c_out_dat_w) when rising_edge(clk);
- round_im <= RESIZE_SVEC(s_round(product_im, c_round_w), c_out_dat_w) when rising_edge(clk);
- end generate;
+ u_requantize_re : entity common_lib.common_requantize
+ generic map (
+ g_representation => "SIGNED",
+ g_lsb_w => c_round_w,
+ g_lsb_round => TRUE,
+ g_lsb_round_clip => FALSE,
+ g_lsb_round_even => g_round_even,
+ g_msb_clip => FALSE,
+ g_msb_clip_symmetric => FALSE,
+ g_pipeline_remove_lsb => c_round_lat,
+ g_pipeline_remove_msb => 0,
+ g_in_dat_w => c_prod_w,
+ g_out_dat_w => c_out_dat_w
+ )
+ port map (
+ clk => clk,
+ in_dat => product_re,
+ out_dat => round_re,
+ out_ovr => open
+ );
+
+ u_requantize_im : entity common_lib.common_requantize
+ generic map (
+ g_representation => "SIGNED",
+ g_lsb_w => c_round_w,
+ g_lsb_round => TRUE,
+ g_lsb_round_clip => FALSE,
+ g_lsb_round_even => g_round_even,
+ g_msb_clip => FALSE,
+ g_msb_clip_symmetric => FALSE,
+ g_pipeline_remove_lsb => c_round_lat,
+ g_pipeline_remove_msb => 0,
+ g_in_dat_w => c_prod_w,
+ g_out_dat_w => c_out_dat_w
+ )
+ port map (
+ clk => clk,
+ in_dat => product_im,
+ out_dat => round_im,
+ out_ovr => open
+ );
end generate;
diff --git a/libraries/dsp/rTwoSDF/tb/vhdl/tb_rTwoSDF.vhd b/libraries/dsp/rTwoSDF/tb/vhdl/tb_rTwoSDF.vhd
index 4a008c8871..48c5eabc75 100644
--- a/libraries/dsp/rTwoSDF/tb/vhdl/tb_rTwoSDF.vhd
+++ b/libraries/dsp/rTwoSDF/tb/vhdl/tb_rTwoSDF.vhd
@@ -268,7 +268,8 @@ begin
g_out_dat_w => g_out_dat_w,
g_stage_dat_w => c_stage_dat_w,
g_guard_w => g_guard_w,
- g_nof_points => g_nof_points
+ g_nof_points => g_nof_points,
+ g_round_even => false -- golden results use round half
)
port map(
clk => clk,
--
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