diff options
Diffstat (limited to 'qtmips_machine/core.cpp')
| -rw-r--r-- | qtmips_machine/core.cpp | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/qtmips_machine/core.cpp b/qtmips_machine/core.cpp index a2cc74b..5768d9c 100644 --- a/qtmips_machine/core.cpp +++ b/qtmips_machine/core.cpp @@ -10,6 +10,7 @@ using namespace machine; #define DM_ALUSRC (1L<<3) #define DM_REGD (1L<<4) #define DM_REGWRITE (1L<<5) +#define DM_ZERO_EXTEND (1L<<6) struct DecodeMap { long flags; @@ -22,6 +23,7 @@ struct DecodeMap { #define NOPE { .flags = 0, NOALU, NOMEM } #define FLAGS_ALU_I (DM_SUPPORTED | DM_ALUSRC | DM_REGWRITE) +#define FLAGS_ALU_I_ZE (DM_SUPPORTED | DM_ALUSRC | DM_REGWRITE | DM_ZERO_EXTEND) // This is map from opcode to signals. static const struct DecodeMap dmap[] = { @@ -37,9 +39,9 @@ static const struct DecodeMap dmap[] = { { .flags = FLAGS_ALU_I, .alu = ALU_OP_ADDU, NOMEM }, // ADDIU { .flags = FLAGS_ALU_I, .alu = ALU_OP_SLT, NOMEM }, // SLTI { .flags = FLAGS_ALU_I, .alu = ALU_OP_SLTU, NOMEM }, // SLTIU - { .flags = FLAGS_ALU_I, .alu = ALU_OP_AND, NOMEM }, // ANDI - { .flags = FLAGS_ALU_I, .alu = ALU_OP_OR, NOMEM }, // ORI - { .flags = FLAGS_ALU_I, .alu = ALU_OP_XOR, NOMEM }, // XORI + { .flags = FLAGS_ALU_I_ZE, .alu = ALU_OP_AND, NOMEM }, // ANDI + { .flags = FLAGS_ALU_I_ZE, .alu = ALU_OP_OR, NOMEM }, // ORI + { .flags = FLAGS_ALU_I_ZE, .alu = ALU_OP_XOR, NOMEM }, // XORI { .flags = FLAGS_ALU_I, .alu = ALU_OP_LUI, NOMEM}, // LUI NOPE, // 16 NOPE, // 17 @@ -128,11 +130,17 @@ struct Core::dtDecode Core::decode(const struct dtFetch &dt) { std::uint32_t val_rs = regs->read_gp(dt.inst.rs()); std::uint32_t val_rt = regs->read_gp(dt.inst.rt()); + std::uint32_t immediate_val; + + if (dec.flags & DM_ZERO_EXTEND) + immediate_val = dt.inst.immediate(); + else + immediate_val = sign_extend(dt.inst.immediate()); emit decode_instruction_value(dt.inst.data()); emit decode_reg1_value(val_rs); emit decode_reg2_value(val_rt); - emit decode_immediate_value(sign_extend(dt.inst.immediate())); + emit decode_immediate_value(immediate_val); emit decode_regw_value((bool)(dec.flags & DM_REGWRITE)); emit decode_memtoreg_value((bool)(dec.flags & DM_MEMREAD)); emit decode_memwrite_value((bool)(dec.flags & DM_MEMWRITE)); @@ -151,6 +159,7 @@ struct Core::dtDecode Core::decode(const struct dtFetch &dt) { .memctl = dec.mem_ctl, .val_rs = val_rs, .val_rt = val_rt, + .immediate_val = immediate_val, .ff_rs = FORWARD_NONE, .ff_rt = FORWARD_NONE, }; @@ -166,7 +175,7 @@ struct Core::dtExecute Core::execute(const struct dtDecode &dt) { std::uint32_t alu_sec = dt.val_rt; if (dt.alusrc) - alu_sec = sign_extend(dt.inst.immediate()); // Sign extend to 32bit + alu_sec = dt.immediate_val; // Sign or zero extend immediate value std::uint32_t alu_val = alu_operate(dt.aluop, dt.val_rs, alu_sec, dt.inst.shamt(), regs); @@ -175,7 +184,7 @@ struct Core::dtExecute Core::execute(const struct dtDecode &dt) { emit execute_reg2_value(dt.val_rt); emit execute_reg1_ff_value(dt.ff_rs); emit execute_reg2_ff_value(dt.ff_rt); - emit execute_immediate_value(sign_extend(dt.inst.immediate())); + emit execute_immediate_value(dt.immediate_val); emit execute_regw_value(dt.regwrite); emit execute_memtoreg_value(dt.memread); emit execute_memread_value(dt.memread); @@ -298,6 +307,7 @@ void Core::dtDecodeInit(struct dtDecode &dt) { dt.aluop = ALU_OP_SLL; dt.val_rs = 0; dt.val_rt = 0; + dt.immediate_val = 0; dt.ff_rs = FORWARD_NONE; dt.ff_rt = FORWARD_NONE; } |