273 lines
10 KiB
C++
273 lines
10 KiB
C++
//: SubX mostly deals with instructions operating on 32-bit operands, but we
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//: still need to deal with raw bytes for strings and so on.
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//: Unfortunately the register encodings when dealing with bytes are a mess.
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//: We need a special case for them.
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:(code)
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string rname_8bit(uint8_t r) {
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switch (r) {
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case 0: return "AL"; // lowest byte of EAX
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case 1: return "CL"; // lowest byte of ECX
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case 2: return "DL"; // lowest byte of EDX
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case 3: return "BL"; // lowest byte of EBX
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case 4: return "AH"; // second lowest byte of EAX
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case 5: return "CH"; // second lowest byte of ECX
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case 6: return "DH"; // second lowest byte of EDX
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case 7: return "BH"; // second lowest byte of EBX
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default: raise << "invalid 8-bit register " << r << '\n' << end(); return "";
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}
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}
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uint8_t* effective_byte_address(uint8_t modrm) {
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uint8_t mod = (modrm>>6);
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uint8_t rm = modrm & 0x7;
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if (mod == 3) {
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// select an 8-bit register
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trace(Callstack_depth+1, "run") << "r/m8 is " << rname_8bit(rm) << end();
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return reg_8bit(rm);
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}
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// the rest is as usual
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return mem_addr_u8(effective_address_number(modrm));
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}
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uint8_t* reg_8bit(uint8_t rm) {
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uint8_t* result = reinterpret_cast<uint8_t*>(&Reg[rm & 0x3].i); // _L register
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if (rm & 0x4)
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++result; // _H register; assumes host is little-endian
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return result;
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}
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:(before "End Initialize Op Names")
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put_new(Name, "88", "copy r8 to r8/m8-at-r32");
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:(code)
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void test_copy_r8_to_mem_at_r32() {
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Reg[EBX].i = 0x224488ab;
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Reg[EAX].i = 0x2000;
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run(
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"== code 0x1\n"
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// op ModR/M SIB displacement immediate
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" 88 18 \n" // copy BL to the byte at *EAX
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// ModR/M in binary: 00 (indirect mode) 011 (src BL) 000 (dest EAX)
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"== data 0x2000\n"
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"f0 cc bb aa\n"
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);
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CHECK_TRACE_CONTENTS(
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"run: copy BL to r8/m8-at-r32\n"
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"run: effective address is 0x00002000 (EAX)\n"
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"run: storing 0xab\n"
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);
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CHECK_EQ(0xaabbccab, read_mem_u32(0x2000));
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}
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:(before "End Single-Byte Opcodes")
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case 0x88: { // copy r8 to r/m8
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const uint8_t modrm = next();
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const uint8_t rsrc = (modrm>>3)&0x7;
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trace(Callstack_depth+1, "run") << "copy " << rname_8bit(rsrc) << " to r8/m8-at-r32" << end();
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// use unsigned to zero-extend 8-bit value to 32 bits
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uint8_t* dest = effective_byte_address(modrm);
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const uint8_t* src = reg_8bit(rsrc);
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*dest = *src; // Read/write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well.
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trace(Callstack_depth+1, "run") << "storing 0x" << HEXBYTE << NUM(*dest) << end();
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break;
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}
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//:
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:(before "End Initialize Op Names")
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put_new(Name, "8a", "copy r8/m8-at-r32 to r8");
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:(code)
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void test_copy_mem_at_r32_to_r8() {
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Reg[EBX].i = 0xaabbcc0f; // one nibble each of lowest byte set to all 0s and all 1s, to maximize value of this test
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Reg[EAX].i = 0x2000;
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run(
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"== code 0x1\n"
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// op ModR/M SIB displacement immediate
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" 8a 18 \n" // copy just the byte at *EAX to BL
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// ModR/M in binary: 00 (indirect mode) 011 (dest EBX) 000 (src EAX)
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"== data 0x2000\n"
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"ab ff ff ff\n" // 0xab with more data in following bytes
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);
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CHECK_TRACE_CONTENTS(
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"run: copy r8/m8-at-r32 to BL\n"
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"run: effective address is 0x00002000 (EAX)\n"
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"run: storing 0xab\n"
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// remaining bytes of EBX are *not* cleared
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"run: EBX now contains 0xaabbccab\n"
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);
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}
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:(before "End Single-Byte Opcodes")
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case 0x8a: { // copy r/m8 to r8
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const uint8_t modrm = next();
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const uint8_t rdest = (modrm>>3)&0x7;
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trace(Callstack_depth+1, "run") << "copy r8/m8-at-r32 to " << rname_8bit(rdest) << end();
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// use unsigned to zero-extend 8-bit value to 32 bits
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const uint8_t* src = effective_byte_address(modrm);
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uint8_t* dest = reg_8bit(rdest);
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trace(Callstack_depth+1, "run") << "storing 0x" << HEXBYTE << NUM(*src) << end();
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*dest = *src; // Read/write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well.
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const uint8_t rdest_32bit = rdest & 0x3;
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trace(Callstack_depth+1, "run") << rname(rdest_32bit) << " now contains 0x" << HEXWORD << Reg[rdest_32bit].u << end();
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break;
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}
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:(code)
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void test_cannot_copy_byte_to_ESP_EBP_ESI_EDI() {
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Reg[ESI].u = 0xaabbccdd;
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Reg[EBX].u = 0x11223344;
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run(
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"== code 0x1\n"
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// op ModR/M SIB displacement immediate
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" 8a f3 \n" // copy just the byte at *EBX to 8-bit register '6'
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// ModR/M in binary: 11 (direct mode) 110 (dest 8-bit 'register 6') 011 (src EBX)
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);
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CHECK_TRACE_CONTENTS(
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// ensure 8-bit register '6' is DH, not ESI
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"run: copy r8/m8-at-r32 to DH\n"
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"run: storing 0x44\n"
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);
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// ensure ESI is unchanged
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CHECK_EQ(Reg[ESI].u, 0xaabbccdd);
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}
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//:
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:(before "End Initialize Op Names")
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put_new(Name, "c6", "copy imm8 to r8/m8-at-r32 (mov)");
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:(code)
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void test_copy_imm8_to_mem_at_r32() {
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Reg[EAX].i = 0x2000;
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run(
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"== code 0x1\n"
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// op ModR/M SIB displacement immediate
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" c6 00 dd \n" // copy to the byte at *EAX
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// ModR/M in binary: 00 (indirect mode) 000 (unused) 000 (dest EAX)
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"== data 0x2000\n"
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"f0 cc bb aa\n"
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);
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CHECK_TRACE_CONTENTS(
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"run: copy imm8 to r8/m8-at-r32\n"
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"run: effective address is 0x00002000 (EAX)\n"
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"run: storing 0xdd\n"
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);
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CHECK_EQ(0xaabbccdd, read_mem_u32(0x2000));
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}
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:(before "End Single-Byte Opcodes")
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case 0xc6: { // copy imm8 to r/m8
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const uint8_t modrm = next();
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const uint8_t src = next();
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trace(Callstack_depth+1, "run") << "copy imm8 to r8/m8-at-r32" << end();
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trace(Callstack_depth+1, "run") << "imm8 is 0x" << HEXWORD << NUM(src) << end();
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const uint8_t subop = (modrm>>3)&0x7; // middle 3 'reg opcode' bits
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if (subop != 0) {
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cerr << "unrecognized subop for opcode c6: " << NUM(subop) << " (only 0/copy currently implemented)\n";
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exit(1);
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}
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// use unsigned to zero-extend 8-bit value to 32 bits
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uint8_t* dest = effective_byte_address(modrm);
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*dest = src; // Write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well.
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trace(Callstack_depth+1, "run") << "storing 0x" << HEXBYTE << NUM(*dest) << end();
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break;
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}
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//:: set flags (setcc)
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:(before "End Initialize Op Names")
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put_new(Name_0f, "94", "set r8/m8-at-rm32 to 1 if equal, if ZF is set, 0 otherwise (setcc/setz/sete)");
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put_new(Name_0f, "95", "set r8/m8-at-rm32 to 1 if not equal, if ZF is not set, 0 otherwise (setcc/setnz/setne)");
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put_new(Name_0f, "9f", "set r8/m8-at-rm32 to 1 if greater (signed), if ZF is unset and SF == OF, 0 otherwise (setcc/setg/setnle)");
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put_new(Name_0f, "97", "set r8/m8-at-rm32 to 1 if greater (unsigned), if ZF is unset and CF is unset, 0 otherwise (setcc/seta/setnbe)");
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put_new(Name_0f, "9d", "set r8/m8-at-rm32 to 1 if greater or equal (signed), if SF == OF, 0 otherwise (setcc/setge/setnl)");
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put_new(Name_0f, "93", "set r8/m8-at-rm32 to 1 if greater or equal (unsigned), if CF is unset, 0 otherwise (setcc/setae/setnb)");
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put_new(Name_0f, "9c", "set r8/m8-at-rm32 to 1 if lesser (signed), if SF != OF, 0 otherwise (setcc/setl/setnge)");
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put_new(Name_0f, "92", "set r8/m8-at-rm32 to 1 if lesser (unsigned), if CF is set, 0 otherwise (setcc/setb/setnae)");
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put_new(Name_0f, "9e", "set r8/m8-at-rm32 to 1 if lesser or equal (signed), if ZF is set or SF != OF, 0 otherwise (setcc/setle/setng)");
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put_new(Name_0f, "96", "set r8/m8-at-rm32 to 1 if lesser or equal (unsigned), if ZF is set or CF is set, 0 otherwise (setcc/setbe/setna)");
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:(before "End Two-Byte Opcodes Starting With 0f")
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case 0x94: { // set r8/m8-at-rm32 if ZF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = ZF;
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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case 0x95: { // set r8/m8-at-rm32 if !ZF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = !ZF;
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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case 0x9f: { // set r8/m8-at-rm32 if !SF and !ZF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = !ZF && SF == OF;
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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case 0x97: { // set r8/m8-at-rm32 if !CF and !ZF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = (!CF && !ZF);
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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case 0x9d: { // set r8/m8-at-rm32 if !SF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = (SF == OF);
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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case 0x93: { // set r8/m8-at-rm32 if !CF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = !CF;
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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case 0x9c: { // set r8/m8-at-rm32 if SF and !ZF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = (SF != OF);
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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case 0x92: { // set r8/m8-at-rm32 if CF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = CF;
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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case 0x9e: { // set r8/m8-at-rm32 if SF or ZF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = (ZF || SF != OF);
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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case 0x96: { // set r8/m8-at-rm32 if ZF or CF
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const uint8_t modrm = next();
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trace(Callstack_depth+1, "run") << "set r8/m8-at-rm32" << end();
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uint8_t* dest = effective_byte_address(modrm);
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*dest = (ZF || CF);
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trace(Callstack_depth+1, "run") << "storing " << NUM(*dest) << end();
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break;
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}
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