From d610c00dea368358edeee08cad2e330d9ebe1c30 Mon Sep 17 00:00:00 2001
From: Eric Kooistra <kooistra@astron.nl>
Date: Mon, 1 Feb 2021 08:27:49 +0100
Subject: [PATCH] Improved and clarified definition of sign of resolution_w in
TO_SREAL().
---
libraries/base/common/src/vhdl/common_pkg.vhd | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/libraries/base/common/src/vhdl/common_pkg.vhd b/libraries/base/common/src/vhdl/common_pkg.vhd
index f26318f930..79591b0b30 100644
--- a/libraries/base/common/src/vhdl/common_pkg.vhd
+++ b/libraries/base/common/src/vhdl/common_pkg.vhd
@@ -1793,12 +1793,13 @@ PACKAGE BODY common_pkg IS
VARIABLE v_real : REAL := TO_SREAL(svec);
BEGIN
-- Then scale to real:
- -- . The resolution_w is the number of bits that LSbit 0 in svec is after or before the fixed point.
- -- . The real value is then scaled by scaling the integer value by 2**resolution_w:
+ -- . The resolution_w is the number of bits that LSbit 0 in svec(HIGH-1 DOWNTO 0) is after
+ -- (when resolution_w > 0), or before (when resolution_w < 0) the fixed point.
+ -- . The real value is then scaled by scaling the integer value by 2**(-1 * resolution_w):
-- . resolution_w = 0 : scale by 2**0 = 1, so no scaling and the value is treated as an integer
-- . resolution_w < 0 : scale up
-- . resolution_w > 0 : scale down
- RETURN v_real * 2.0**REAL(resolution_w);
+ RETURN v_real * 2.0**REAL(-1 * resolution_w);
END;
--
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