tcg/riscv: Add the immediate encoders

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Michael Clark <mjc@sifive.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <d54dc56303fd1b0d7ed53869de2dbb59b111c7ca.1545246859.git.alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tcg/riscv/tcg-target.inc.c

@@ -284,3 +284,93 @@ typedef enum {
 
     OPC_FENCE = 0x0000000f,
 } RISCVInsn;
+
+/*
+ * RISC-V immediate and instruction encoders (excludes 16-bit RVC)
+ */
+
+/* Type-R */
+
+static int32_t encode_r(RISCVInsn opc, TCGReg rd, TCGReg rs1, TCGReg rs2)
+{
+    return opc | (rd & 0x1f) << 7 | (rs1 & 0x1f) << 15 | (rs2 & 0x1f) << 20;
+}
+
+/* Type-I */
+
+static int32_t encode_imm12(uint32_t imm)
+{
+    return (imm & 0xfff) << 20;
+}
+
+static int32_t encode_i(RISCVInsn opc, TCGReg rd, TCGReg rs1, uint32_t imm)
+{
+    return opc | (rd & 0x1f) << 7 | (rs1 & 0x1f) << 15 | encode_imm12(imm);
+}
+
+/* Type-S */
+
+static int32_t encode_simm12(uint32_t imm)
+{
+    int32_t ret = 0;
+
+    ret |= (imm & 0xFE0) << 20;
+    ret |= (imm & 0x1F) << 7;
+
+    return ret;
+}
+
+static int32_t encode_s(RISCVInsn opc, TCGReg rs1, TCGReg rs2, uint32_t imm)
+{
+    return opc | (rs1 & 0x1f) << 15 | (rs2 & 0x1f) << 20 | encode_simm12(imm);
+}
+
+/* Type-SB */
+
+static int32_t encode_sbimm12(uint32_t imm)
+{
+    int32_t ret = 0;
+
+    ret |= (imm & 0x1000) << 19;
+    ret |= (imm & 0x7e0) << 20;
+    ret |= (imm & 0x1e) << 7;
+    ret |= (imm & 0x800) >> 4;
+
+    return ret;
+}
+
+static int32_t encode_sb(RISCVInsn opc, TCGReg rs1, TCGReg rs2, uint32_t imm)
+{
+    return opc | (rs1 & 0x1f) << 15 | (rs2 & 0x1f) << 20 | encode_sbimm12(imm);
+}
+
+/* Type-U */
+
+static int32_t encode_uimm20(uint32_t imm)
+{
+    return imm & 0xfffff000;
+}
+
+static int32_t encode_u(RISCVInsn opc, TCGReg rd, uint32_t imm)
+{
+    return opc | (rd & 0x1f) << 7 | encode_uimm20(imm);
+}
+
+/* Type-UJ */
+
+static int32_t encode_ujimm20(uint32_t imm)
+{
+    int32_t ret = 0;
+
+    ret |= (imm & 0x0007fe) << (21 - 1);
+    ret |= (imm & 0x000800) << (20 - 11);
+    ret |= (imm & 0x0ff000) << (12 - 12);
+    ret |= (imm & 0x100000) << (31 - 20);
+
+    return ret;
+}
+
+static int32_t encode_uj(RISCVInsn opc, TCGReg rd, uint32_t imm)
+{
+    return opc | (rd & 0x1f) << 7 | encode_ujimm20(imm);
+}