From cbf75be7ee77a3600d948e86476dba323a32b2c1 Mon Sep 17 00:00:00 2001
From: Yuanhsi Chung <freshliver.cys@gmail.com>
Date: Thu, 25 Jan 2024 15:38:15 +0800
Subject: [PATCH] Fix immediate width of ImmJ and ImmB

---
 src/isa/rv_i_ext.h     |  8 ++++----
 test/tst_assembler.cpp | 12 ++++++------
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/src/isa/rv_i_ext.h b/src/isa/rv_i_ext.h
index 9d9bc202..302b446e 100644
--- a/src/isa/rv_i_ext.h
+++ b/src/isa/rv_i_ext.h
@@ -309,7 +309,7 @@ struct Lui : public Instr<Lui, RVISA::OpcodeID::LUI> {
 
 namespace TypeJ {
 
-/// A RISC-V signed immediate field with an input width of 21 bits.
+/// A RISC-V signed immediate field with an input width of 20 bits.
 /// Used in J-Type instructions.
 ///
 /// It is defined as:
@@ -321,7 +321,7 @@ namespace TypeJ {
 ///  - Imm[0]     = 0
 constexpr static unsigned VALID_INDEX = 1;
 template <unsigned index>
-struct ImmJ : public ImmSym<index, 21, Repr::Signed,
+struct ImmJ : public ImmSym<index, 20, Repr::Signed,
                             ImmPartSet<ImmPart<20, 31, 31>, ImmPart<12, 12, 19>,
                                        ImmPart<11, 20, 20>, ImmPart<1, 21, 30>>,
                             SymbolType::Relative> {
@@ -489,7 +489,7 @@ enum class Funct3 {
   BGEU = 0b111
 };
 
-/// A RISC-V signed immediate field with an input width of 13 bits.
+/// A RISC-V signed immediate field with an input width of 12 bits.
 /// Used in B-Type instructions.
 ///
 /// It is defined as:
@@ -500,7 +500,7 @@ enum class Funct3 {
 ///  - Imm[0]     = 0
 constexpr static unsigned VALID_INDEX = 2;
 template <unsigned index>
-struct ImmB : public ImmSym<index, 13, Repr::Signed,
+struct ImmB : public ImmSym<index, 12, Repr::Signed,
                             ImmPartSet<ImmPart<12, 31, 31>, ImmPart<11, 7, 7>,
                                        ImmPart<5, 25, 30>, ImmPart<1, 8, 11>>,
                             SymbolType::Relative> {
diff --git a/test/tst_assembler.cpp b/test/tst_assembler.cpp
index fac4d8a8..654bbd84 100644
--- a/test/tst_assembler.cpp
+++ b/test/tst_assembler.cpp
@@ -270,12 +270,12 @@ void tst_Assembler::tst_immBitRange() {
   testAssemble(QStringList() << "lui   a0 0x100000", Expect::Fail);
   testAssemble(QStringList() << "auipc a0 0x0FFFFF", Expect::Success);
   testAssemble(QStringList() << "auipc a0 0x100000", Expect::Fail);
-  // J-type: 21 bits imm (ImmJ)
-  testAssemble(QStringList() << "jal   x0 0x1FFFFF", Expect::Success);
-  testAssemble(QStringList() << "jal   x0 0x200000", Expect::Fail);
-  // B-type: 13 bits imm (ImmB)
-  testAssemble(QStringList() << "beq   a0 x0 0x1FFF", Expect::Success);
-  testAssemble(QStringList() << "beq   a0 x0 0x2000", Expect::Fail);
+  // J-type: 20 bits imm (ImmJ)
+  testAssemble(QStringList() << "jal   x0 0x0FFFFF", Expect::Success);
+  testAssemble(QStringList() << "jal   x0 0x100000", Expect::Fail);
+  // B-type: 12 bits imm (ImmB)
+  testAssemble(QStringList() << "beq   a0 x0 0x0FFF", Expect::Success);
+  testAssemble(QStringList() << "beq   a0 x0 0x1000", Expect::Fail);
   // pseudo: 32 bits imm
   testAssemble(QStringList() << "li    a0 0xFFFFFFFF", Expect::Success);
   testAssemble(QStringList() << "li    a0 0x100000000", Expect::Fail);