From 15398c34d38489bf14a100bbf01fb9fb4c7e46cb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Karel=20Ko=C4=8D=C3=AD?= Date: Tue, 12 Dec 2017 18:53:02 +0100 Subject: Implement branch and jump instructions --- qtmips_machine/alu.cpp | 4 ++ qtmips_machine/alu.h | 2 + qtmips_machine/core.cpp | 140 +++++++++++++++++++++++++++---------- qtmips_machine/core.h | 10 ++- qtmips_machine/memory.cpp | 3 +- qtmips_machine/registers.cpp | 4 ++ qtmips_machine/registers.h | 1 + qtmips_machine/tests/testcore.cpp | 99 ++++++++++++++++++++++++-- qtmips_machine/tests/tst_machine.h | 4 ++ 9 files changed, 222 insertions(+), 45 deletions(-) (limited to 'qtmips_machine') diff --git a/qtmips_machine/alu.cpp b/qtmips_machine/alu.cpp index 0350412..73c49e4 100644 --- a/qtmips_machine/alu.cpp +++ b/qtmips_machine/alu.cpp @@ -17,6 +17,10 @@ std::uint32_t alu_operate(enum AluOp operation, std::uint32_t s, std::uint32_t t case ALU_OP_SRAV: // TODO is this correct implementation? (Should we be masking top most bit?) return ((t & 0x7fffffff) >> s) | (t & 0x80000000); + case ALU_OP_JR: + case ALU_OP_JALR: + // Do nothing as we solve this when we are handling program counter in instruction decode (handle_pc) + return 0; case ALU_OP_MOVZ: // We do this just to implement valid alu operation but we have to evaluate comparison way before this to disable register write return t == 0 ? s : 0; diff --git a/qtmips_machine/alu.h b/qtmips_machine/alu.h index 4818bb1..95042f4 100644 --- a/qtmips_machine/alu.h +++ b/qtmips_machine/alu.h @@ -14,6 +14,8 @@ enum AluOp : std::uint8_t { ALU_OP_SLLV, ALU_OP_SRLV = 6, ALU_OP_SRAV, + ALU_OP_JR, + ALU_OP_JALR, ALU_OP_MOVZ = 10, ALU_OP_MOVN, ALU_OP_MFHI = 16, diff --git a/qtmips_machine/core.cpp b/qtmips_machine/core.cpp index 20c1b74..93b83dd 100644 --- a/qtmips_machine/core.cpp +++ b/qtmips_machine/core.cpp @@ -7,7 +7,6 @@ #define DM_ALUSRC (1L<<3) #define DM_REGD (1L<<4) #define DM_REGWRITE (1L<<5) -#define DM_BRANCH (1L<<6) struct DecodeMap { long flags; @@ -16,20 +15,21 @@ // This is temporally operation place holder -#define NOPE { .flags = 0, .alu = ALU_OP_SLL } +#define NOALU .alu = ALU_OP_SLL +#define NOPE { .flags = 0, NOALU } #define FLAGS_ALU_I (DM_SUPPORTED | DM_ALUSRC | DM_REGWRITE) // This is map from opcode to signals. static const struct DecodeMap dmap[] = { - { .flags = DM_SUPPORTED | DM_REGD | DM_REGWRITE, .alu = ALU_OP_SLL }, // Alu operations - NOPE, // Branch on alu operations - NOPE, // J + { .flags = DM_SUPPORTED | DM_REGD | DM_REGWRITE, NOALU }, // Alu operations (aluop is decoded from function explicitly) + { .flags = DM_SUPPORTED, NOALU }, // REGIMM (BLTZ, BGEZ, ) + { .flags = DM_SUPPORTED, NOALU }, // J NOPE, // JAL - NOPE, // BEQ - NOPE, // BNE - NOPE, // BLEZ - NOPE, // BGTZ + { .flags = DM_SUPPORTED, NOALU }, // BEQ + { .flags = DM_SUPPORTED, NOALU }, // BNE + { .flags = DM_SUPPORTED, NOALU }, // BLEZ + { .flags = DM_SUPPORTED, NOALU }, // BGTZ { .flags = FLAGS_ALU_I, .alu = ALU_OP_ADD }, // ADDI { .flags = FLAGS_ALU_I, .alu = ALU_OP_ADDU }, // ADDIU { .flags = FLAGS_ALU_I, .alu = ALU_OP_SLT }, // SLTI @@ -96,7 +96,6 @@ Core::Core(Registers *regs, MemoryAccess *mem) { struct Core::dtFetch Core::fetch() { // TODO signals Instruction inst(mem->read_word(regs->read_pc())); - regs->pc_inc(); return { .inst = inst }; @@ -104,10 +103,14 @@ struct Core::dtFetch Core::fetch() { struct Core::dtDecode Core::decode(struct dtFetch dt) { struct DecodeMap dec = dmap[dt.inst.opcode()]; - if (!dec.flags & DM_SUPPORTED) + if (!(dec.flags & DM_SUPPORTED)) // TODO message throw QTMIPS_EXCEPTION(UnsupportedInstruction, "", ""); + // TODO solve forwarding somehow in here + std::uint32_t rs = regs->read_gp(dt.inst.rs()); + std::uint32_t rt = regs->read_gp(dt.inst.rt()); + return { .inst = dt.inst, .mem2reg = dec.flags & DM_MEM2REG, @@ -115,10 +118,9 @@ struct Core::dtDecode Core::decode(struct dtFetch dt) { .alusrc = dec.flags & DM_ALUSRC, .regd = dec.flags & DM_REGD, .regwrite = dec.flags & DM_REGWRITE, - .branch = dec.flags & DM_BRANCH, .aluop = dt.inst.opcode() == 0 ? (enum AluOp)dt.inst.funct() : dec.alu, - .val_rs = regs->read_gp(dt.inst.rs()), - .val_rt = regs->read_gp(dt.inst.rt()), + .val_rs = rs, + .val_rt = rt, }; // TODO on jump there should be delay slot. Does processor addes it or compiler. And do we care? } @@ -154,9 +156,88 @@ void Core::writeback(struct dtMemory dt) { } } +void Core::handle_pc(struct dtDecode dt) { + // TODO signals + bool branch = false; + bool link = false; + // TODO implement link + + switch (dt.inst.opcode()) { + case 0: // JR (JALR) + if (dt.inst.funct() == ALU_OP_JR || dt.inst.funct() == ALU_OP_JALR) { + regs->pc_abs_jmp(dt.val_rs); + return; + } + break; + case 1: // REGIMM instruction + //switch (dt.inst.rt() & 0xF) { // Should be used when linking is supported + switch (dt.inst.rt()) { + case 0: // BLTZ(AL) + branch = (std::int32_t)dt.val_rs < 0; + break; + case 1: // BGEZ(AL) + branch = (std::int32_t)dt.val_rs >= 0; + break; + default: + throw QTMIPS_EXCEPTION(UnsupportedInstruction, "REGIMM instruction with unknown rt code", QString::number(dt.inst.rt(), 16)); + } + link = dt.inst.rs() & 0x10; + break; + case 2: // J + case 3: // JAL + regs->pc_abs_jmp_28(dt.inst.address() << 2); + return; + case 4: // BEQ + branch = dt.val_rs == dt.val_rt; + break; + case 5: // BNE + branch = dt.val_rs != dt.val_rt; + break; + case 6: // BLEZ + branch = (std::int32_t)dt.val_rs <= 0; + break; + case 7: // BGTZ + branch = (std::int32_t)dt.val_rs > 0; + break; + } + + if (branch) + regs->pc_jmp((std::int32_t)(((dt.inst.immediate() & 0x7fff) << 2) | ((dt.inst.immediate() & 0x8000) << 16))); + else + regs->pc_inc(); +} + +void Core::dtFetchInit(struct dtFetch &dt) { + dt.inst = Instruction(0x00); +} + +void Core::dtDecodeInit(struct dtDecode &dt) { + dt.inst = Instruction(0x00); + dt.mem2reg = false; + dt.memwrite = false; + dt.alusrc = false; + dt.regd = false; + dt.regwrite = false; + dt.aluop = ALU_OP_SLL; + dt.val_rs = 0; + dt.val_rt = 0; +} + +void Core::dtExecuteInit(struct dtExecute &dt) { + dt.regwrite = false; + dt.rwrite = false; + dt.alu_val = 0; +} + +void Core::dtMemoryInit(struct dtMemory &dt) { + dt.regwrite = false; + dt.rwrite = false; + dt.alu_val = 0; +} + CoreSingle::CoreSingle(Registers *regs, MemoryAccess *mem) : \ Core(regs, mem) { - // Nothing to do + dtDecodeInit(jmp_delay_decode); } void CoreSingle::step() { @@ -165,32 +246,16 @@ void CoreSingle::step() { struct dtExecute e = execute(d); struct dtMemory m = memory(e); writeback(m); + handle_pc(jmp_delay_decode); + jmp_delay_decode = d; // Copy current decode } CorePipelined::CorePipelined(Registers *regs, MemoryAccess *mem) : \ Core(regs, mem) { - // Initialize to NOPE // - // dtFetch - dt_f.inst = Instruction(0x00); - // dtDecode - dt_d.inst = dt_f.inst; - dt_d.mem2reg = false; - dt_d.memwrite = false; - dt_d.alusrc = false; - dt_d.regd = false; - dt_d.regwrite = false; - dt_d.branch = false; - dt_d.aluop = ALU_OP_SLL; - dt_d.val_rs = 0; - dt_d.val_rt = 0; - // dtExecute - dt_e.regwrite = dt_d.regwrite; - dt_e.rwrite = dt_d.regwrite; - dt_e.alu_val = 0; - // dtMemory - dt_m.regwrite = dt_e.regwrite; - dt_m.rwrite = dt_e.rwrite; - dt_m.alu_val = dt_e.alu_val; + dtFetchInit(dt_f); + dtDecodeInit(dt_d); + dtExecuteInit(dt_e); + dtMemoryInit(dt_m); } void CorePipelined::step() { @@ -200,4 +265,5 @@ void CorePipelined::step() { dt_e = execute(dt_d); dt_d = decode(dt_f); dt_f = fetch(); + handle_pc(dt_d); } diff --git a/qtmips_machine/core.h b/qtmips_machine/core.h index b566a38..6366088 100644 --- a/qtmips_machine/core.h +++ b/qtmips_machine/core.h @@ -31,7 +31,6 @@ protected: bool alusrc; // If second value to alu is immediate value (rt used otherwise) bool regd; // If rd is used (otherwise rt is used for write target) bool regwrite; // If output should be written back to register (which one depends on regd) - bool branch; // If this is branch instruction enum AluOp aluop; // Decoded ALU operation std::uint32_t val_rs; // Value from register rs std::uint32_t val_rt; // Value from register rt @@ -54,7 +53,13 @@ protected: struct dtExecute execute(struct dtDecode); struct dtMemory memory(struct dtExecute); void writeback(struct dtMemory); + void handle_pc(struct dtDecode); + // Initialize structures to NOPE instruction + void dtFetchInit(struct dtFetch &dt); + void dtDecodeInit(struct dtDecode &dt); + void dtExecuteInit(struct dtExecute &dt); + void dtMemoryInit(struct dtMemory &dt); }; class CoreSingle : public Core { @@ -62,6 +67,9 @@ public: CoreSingle(Registers *regs, MemoryAccess *mem); void step(); + +private: + struct Core::dtDecode jmp_delay_decode; }; class CorePipelined : public Core { diff --git a/qtmips_machine/memory.cpp b/qtmips_machine/memory.cpp index ef4c7e2..282a9e9 100644 --- a/qtmips_machine/memory.cpp +++ b/qtmips_machine/memory.cpp @@ -240,8 +240,9 @@ union MemoryTree *Memory::copy_section_tree(const union MemoryTree *mt, size_t d union MemoryTree *nmt = allocate_section_tree(); if (depth < (MEMORY_TREE_H - 1)) { // Following level is memory tree for (int i = 0; i < MEMORY_TREE_LEN; i++) { - if (mt[i].mt != nullptr) + if (mt[i].mt != nullptr) { nmt[i].mt = copy_section_tree(mt[i].mt, depth + 1); + } } } else { // Following level is memory section for (int i = 0; i < MEMORY_TREE_LEN; i++) { diff --git a/qtmips_machine/registers.cpp b/qtmips_machine/registers.cpp index 5bb852e..a18421e 100644 --- a/qtmips_machine/registers.cpp +++ b/qtmips_machine/registers.cpp @@ -46,6 +46,10 @@ void Registers::pc_abs_jmp(std::uint32_t address) { this->pc = address; } +void Registers::pc_abs_jmp_28(std::uint32_t address) { + this->pc_abs_jmp((pc & 0xF0000000) | (address & 0x0FFFFFFF)); +} + std::uint32_t Registers::read_gp(std::uint8_t i) const { SANITY_ASSERT(i < 32, QString("Trying to read from register ") + QString(i)); if (!i) // $0 always reads as 0 diff --git a/qtmips_machine/registers.h b/qtmips_machine/registers.h index 387b59d..dd7e393 100644 --- a/qtmips_machine/registers.h +++ b/qtmips_machine/registers.h @@ -14,6 +14,7 @@ public: std::uint32_t pc_inc(); // Increment program counter by four bytes std::uint32_t pc_jmp(std::int32_t offset); // Relative jump from current location in program counter void pc_abs_jmp(std::uint32_t address); // Absolute jump in program counter (write to pc) + void pc_abs_jmp_28(std::uint32_t address); // Absolute jump in current 256MB section (basically J implementation) std::uint32_t read_gp(std::uint8_t i) const; // Read general-purpose register void write_gp(std::uint8_t i, std::uint32_t value); // Write general-purpose register diff --git a/qtmips_machine/tests/testcore.cpp b/qtmips_machine/tests/testcore.cpp index 27a49b4..593483a 100644 --- a/qtmips_machine/tests/testcore.cpp +++ b/qtmips_machine/tests/testcore.cpp @@ -175,9 +175,6 @@ void MachineTests::pipecore_regs_data() { core_regs_data(); } -#include -using namespace std; - void MachineTests::singlecore_regs() { QFETCH(Instruction, i); QFETCH(Registers, init); @@ -208,16 +205,106 @@ void MachineTests::pipecore_regs() { res.pc_jmp(0x14); CorePipelined core(&init, &mem_used); - for (int i = 0; i < 4; i++) { + for (int i = 0; i < 5; i++) core.step(); // Fire steps for five pipelines stages - } - core.step(); //cout << "well:" << init.read_gp(26) << ":" << regs_used.read_gp(26) << endl; QCOMPARE(init, res); // After doing changes from initial state this should be same state as in case of passed expected result QCOMPARE(mem, mem_used); // There should be no change in memory } +static void core_jmp_data() { + QTest::addColumn("i"); + QTest::addColumn("regs"); + QTest::addColumn("pc"); + + Registers regs; + regs.write_gp(14, -22); + regs.write_gp(15, 22); + regs.write_gp(16, -22); + QTest::newRow("B") << Instruction(4, 0, 0, 61) \ + << regs \ + << regs.read_pc() + 4 + (61 << 2); + QTest::newRow("BEQ") << Instruction(4, 14, 16, 61) \ + << regs \ + << regs.read_pc() + 4 + (61 << 2); + QTest::newRow("BNE") << Instruction(5, 14, 15, 61) \ + << regs \ + << regs.read_pc() + 4 + (61 << 2); + QTest::newRow("BGEZ") << Instruction(1, 15, 1, 61) \ + << regs \ + << regs.read_pc() + 4 + (61 << 2); + QTest::newRow("BGTZ") << Instruction(7, 15, 0, 61) \ + << regs \ + << regs.read_pc() + 4 + (61 << 2); + QTest::newRow("BLEZ") << Instruction(6, 14, 0, 61) \ + << regs \ + << regs.read_pc() + 4 + (61 << 2); + QTest::newRow("BLTZ") << Instruction(1, 14, 0, 61) \ + << regs \ + << regs.read_pc() + 4 + (61 << 2); + QTest::newRow("J") << Instruction(2, 24) \ + << regs \ + << 0x80000000 + (24 << 2); + /* + QTest::newRow("JR") << Instruction(1, 15, 0, 61) \ + << regs \ + << regs.read_pc() + (24 << 2); + */ +} + +void MachineTests::singlecore_jmp_data() { + core_jmp_data(); +} + +void MachineTests::pipecore_jmp_data() { + core_jmp_data(); +} + +void MachineTests::singlecore_jmp() { + QFETCH(Instruction, i); + QFETCH(Registers, regs); + QFETCH(std::uint32_t, pc); + + Memory mem; + mem.write_word(regs.read_pc(), i.data()); + Memory mem_used(mem); + Registers regs_used(regs); + + CoreSingle core(®s_used, &mem_used); + core.step(); + QCOMPARE(regs.read_pc() + 4, regs_used.read_pc()); // First execute delay slot + core.step(); + QCOMPARE(pc, regs_used.read_pc()); // Now do jump + + QCOMPARE(mem, mem_used); // There should be no change in memory + regs_used.pc_abs_jmp(regs.read_pc()); // Reset program counter before we do registers compare + QCOMPARE(regs, regs_used); // There should be no change in registers now +} + +void MachineTests::pipecore_jmp() { + QFETCH(Instruction, i); + QFETCH(Registers, regs); + QFETCH(std::uint32_t, pc); + + Memory mem; + mem.write_word(regs.read_pc(), i.data()); + Memory mem_used(mem); + Registers regs_used(regs); + + CorePipelined core(®s_used, &mem_used); + core.step(); + QCOMPARE(regs.read_pc() + 4, regs_used.read_pc()); // First just fetch + core.step(); + QCOMPARE(pc, regs_used.read_pc()); // Now do jump + for (int i = 0; i < 3; i++) + core.step(); // Follow up with three other steps to complete pipeline to be sure that instruction has no side effects + + QCOMPARE(mem, mem_used); // There should be no change in memory + regs.pc_abs_jmp(pc + 12); // Set reference pc to three more instructions later (where regs_used should be) + QCOMPARE(regs, regs_used); // There should be no change in registers now (except pc) +} + void MachineTests::core_mem_data() { } diff --git a/qtmips_machine/tests/tst_machine.h b/qtmips_machine/tests/tst_machine.h index 3feaddd..9b33e68 100644 --- a/qtmips_machine/tests/tst_machine.h +++ b/qtmips_machine/tests/tst_machine.h @@ -34,6 +34,10 @@ private Q_SLOTS: void singlecore_regs_data(); void pipecore_regs(); void pipecore_regs_data(); + void singlecore_jmp(); + void singlecore_jmp_data(); + void pipecore_jmp(); + void pipecore_jmp_data(); void core_mem(); void core_mem_data(); }; -- cgit v1.2.3