riscemu/decoder/decoder.py

@@ -54,6 +54,11 @@ def name_from_insn(ins: int):
         raise RuntimeError(f"Invalid instruction in ebreak/ecall region: {ins:x}")
 
     fun7 = funct7(ins)
+    if opcode == 0b1011 and fun3 == 0b10:
+        # ignore the two aq/lr bits located in the fun7 block
+        # riscemu has no memory reordering, therefore we don't need to look at these bits ever
+        fun7 = fun7 >> 2
+
     if fun7 in dec:
         if opcode == 0x0C or (opcode == 0x04 and fun3 == 5):
             dec = dec[fun7]

riscemu/decoder/formats.py

@@ -112,5 +112,6 @@ INSTRUCTION_ARGS_DECODER: Dict[int, Callable[[int], List[int]]] = {
     0x18: decode_b,
     0x19: decode_i,
     0x1b: decode_j,
-    0x1c: decode_i_unsigned
+    0x1c: decode_i_unsigned,
+    0b1011: decode_r
 }

riscemu/decoder/instruction_table.py

@@ -67,3 +67,15 @@ RV32[0x0C][5][1] = "divu"
 RV32[0x0C][6][1] = "rem"
 RV32[0x0C][7][1] = "remu"
 
+# rv32a
+RV32[0b1011][0b10][0b00010] = "lr.w"
+RV32[0b1011][0b10][0b00011] = "sc.w"
+RV32[0b1011][0b10][0b00001] = "amoswap.w"
+RV32[0b1011][0b10][0b00000] = "amoadd.w"
+RV32[0b1011][0b10][0b00100] = "amoxor.w"
+RV32[0b1011][0b10][0b01100] = "amoand.w"
+RV32[0b1011][0b10][0b01000] = "amoor.w"
+RV32[0b1011][0b10][0b10000] = "amomin.w"
+RV32[0b1011][0b10][0b10100] = "amomax.w"
+RV32[0b1011][0b10][0b11000] = "amominu.w"
+RV32[0b1011][0b10][0b11100] = "amomaxu.w"

riscemu/instructions/RV32A.py

@@ -0,0 +1,78 @@
+from .InstructionSet import InstructionSet, LoadedInstruction
+from ..Exceptions import INS_NOT_IMPLEMENTED
+from ..helpers import int_from_bytes, int_to_bytes, to_unsigned, to_signed
+
+
+class RV32A(InstructionSet):
+    """
+    The RV32A instruction set. Currently, load-reserved and store conditionally are not supported
+    due to limitations in the way the MMU is implemented. Maybe a later implementation will add support
+    for this?
+    """
+
+    def instruction_lr_w(self, ins: 'LoadedInstruction'):
+        INS_NOT_IMPLEMENTED(ins)
+
+    def instruction_sc_w(self, ins: 'LoadedInstruction'):
+        INS_NOT_IMPLEMENTED(ins)
+
+    def instruction_amoswap_w(self, ins: 'LoadedInstruction'):
+        dest, addr, val = self.parse_rd_rs_rs(ins)
+        if dest == 'zero':
+            self.mmu.write(addr, int_to_bytes(addr, 4))
+        else:
+            old = int_from_bytes(self.mmu.read(addr, 4))
+            self.mmu.write(addr, int_to_bytes(val, 4))
+            self.regs.set(dest, old)
+
+    def instruction_amoadd_w(self, ins: 'LoadedInstruction'):
+        dest, addr, val = self.parse_rd_rs_rs(ins)
+        old = int_from_bytes(self.mmu.read(addr, 4))
+        self.mmu.write(addr, int_to_bytes(old + val, 4))
+        self.regs.set(dest, old)
+
+    def instruction_amoand_w(self, ins: 'LoadedInstruction'):
+        dest, addr, val = self.parse_rd_rs_rs(ins)
+        old = int_from_bytes(self.mmu.read(addr, 4))
+        self.mmu.write(addr, int_to_bytes(old & val, 4))
+        self.regs.set(dest, old)
+
+    def instruction_amoor_w(self, ins: 'LoadedInstruction'):
+        dest, addr, val = self.parse_rd_rs_rs(ins)
+        old = int_from_bytes(self.mmu.read(addr, 4))
+        self.mmu.write(addr, int_to_bytes(old | val, 4))
+        self.regs.set(dest, old)
+
+    def instruction_amoxor_w(self, ins: 'LoadedInstruction'):
+        dest, addr, val = self.parse_rd_rs_rs(ins)
+        old = int_from_bytes(self.mmu.read(addr, 4))
+        self.mmu.write(addr, int_to_bytes(old ^ val, 4))
+        self.regs.set(dest, old)
+
+    def instruction_amomax_w(self, ins: 'LoadedInstruction'):
+        dest, addr, val = self.parse_rd_rs_rs(ins)
+        old = int_from_bytes(self.mmu.read(addr, 4))
+        self.mmu.write(addr, int_to_bytes(max(old, val), 4))
+        self.regs.set(dest, old)
+
+    def instruction_amomaxu_w(self, ins: 'LoadedInstruction'):
+        dest, addr, val = self.parse_rd_rs_rs(ins)
+        val = to_unsigned(val)
+        old = int_from_bytes(self.mmu.read(addr, 4), unsigned=True)
+
+        self.mmu.write(addr, int_to_bytes(to_signed(max(old, val)), 4))
+        self.regs.set(dest, old)
+
+    def instruction_amomin_w(self, ins: 'LoadedInstruction'):
+        dest, addr, val = self.parse_rd_rs_rs(ins)
+        old = int_from_bytes(self.mmu.read(addr, 4))
+        self.mmu.write(addr, int_to_bytes(min(old, val), 4))
+        self.regs.set(dest, old)
+
+    def instruction_amominu_w(self, ins: 'LoadedInstruction'):
+        dest, addr, val = self.parse_rd_rs_rs(ins)
+        val = to_unsigned(val)
+        old = int_from_bytes(self.mmu.read(addr, 4), unsigned=True)
+
+        self.mmu.write(addr, int_to_bytes(to_signed(min(old, val)), 4))
+        self.regs.set(dest, old)

riscemu/instructions/__init__.py

@@ -9,7 +9,8 @@ This package holds all instruction sets, available to the processor
 from .InstructionSet import InstructionSet
 from .RV32M import RV32M
 from .RV32I import RV32I
+from .RV32A import RV32A
 
 InstructionSetDict = {
-    v.__name__: v for v in [RV32I, RV32M]
+    v.__name__: v for v in [RV32I, RV32M, RV32A]
 }

riscemu/priv/PrivCPU.py

@@ -14,7 +14,7 @@ from .PrivMMU import PrivMMU
 from ..IO import TextIO
 from .PrivRV32I import PrivRV32I
 from .privmodes import PrivModes
-from ..instructions.RV32M import RV32M
+from ..instructions import RV32A, RV32M
 import json
 
 if typing.TYPE_CHECKING:
@@ -48,7 +48,7 @@ class PrivCPU(CPU):
     """
 
     def __init__(self, conf, mmu: PrivMMU):
-        super().__init__(conf, [PrivRV32I, RV32M])
+        super().__init__(conf, [PrivRV32I, RV32M, RV32A])
         self.mode: PrivModes = PrivModes.MACHINE
 
         mmu.set_cpu(self)