//: operating on memory at the address provided by some register :(scenario add_r32_to_mem_at_r32) % Reg[3].i = 0x10; % Reg[0].i = 0x60; # word in addresses 0x60-0x63 has value 1 % Mem.at(0x60) = 1; # op ModR/M SIB displacement immediate 01 18 # add EBX (reg 3) to *EAX (reg 0) +run: add reg 3 to effective address +run: effective address is mem at address 0x60 (reg 0) +run: storing 0x00000011 :(before "End Mod Special-cases") case 0: // mod 0 is usually indirect addressing switch (rm) { default: trace(2, "run") << "effective address is mem at address 0x" << std::hex << Reg[rm].u << " (reg " << NUM(rm) << ")" << end(); assert(Reg[rm].u + sizeof(int32_t) <= Mem.size()); result = reinterpret_cast(&Mem.at(Reg[rm].u)); // rely on the host itself being in little-endian order break; // End Mod 0 Special-cases } break; //: :(scenario add_mem_at_r32_to_r32) % Reg[0].i = 0x60; % Reg[3].i = 0x10; % Mem.at(0x60) = 1; # op ModR/M SIB displacement immediate 03 18 # add *EAX (reg 0) to EBX (reg 3) +run: add effective address to reg 3 +run: effective address is mem at address 0x60 (reg 0) +run: storing 0x00000011 :(before "End Single-Byte Opcodes") case 0x03: { // add r/m32 to r32 uint8_t modrm = next(); uint8_t arg1 = (modrm>>3)&0x7; trace(2, "run") << "add effective address to reg " << NUM(arg1) << end(); const int32_t* arg2 = effective_address(modrm); BINARY_ARITHMETIC_OP(+, Reg[arg1].i, *arg2); break; } //:: subtract :(scenario subtract_r32_from_mem_at_r32) % Reg[0].i = 0x60; % Mem.at(0x60) = 10; % Reg[3].i = 1; # op ModRM SIB displacement immediate 29 18 # subtract EBX (reg 3) from *EAX (reg 0) +run: subtract reg 3 from effective address +run: effective address is mem at address 0x60 (reg 0) +run: storing 0x00000009 //: :(scenario subtract_mem_at_r32_from_r32) % Reg[0].i = 0x60; % Mem.at(0x60) = 1; % Reg[3].i = 10; # op ModRM SIB displacement immediate 2b 18 # subtract *EAX (reg 0) from EBX (reg 3) +run: subtract effective address from reg 3 +run: effective address is mem at address 0x60 (reg 0) +run: storing 0x00000009 :(before "End Single-Byte Opcodes") case 0x2b: { // subtract r/m32 from r32 uint8_t modrm = next(); uint8_t arg1 = (modrm>>3)&0x7; trace(2, "run") << "subtract effective address from reg " << NUM(arg1) << end(); const int32_t* arg2 = effective_address(modrm); BINARY_ARITHMETIC_OP(-, Reg[arg1].i, *arg2); break; } //:: and :(scenario and_r32_with_mem_at_r32) % Reg[0].i = 0x60; % Mem.at(0x60) = 0x0d; % Mem.at(0x61) = 0x0c; % Mem.at(0x62) = 0x0b; % Mem.at(0x63) = 0x0a; % Reg[3].i = 0xff; # op ModRM SIB displacement immediate 21 18 # and EBX (reg 3) with *EAX (reg 0) +run: and reg 3 with effective address +run: effective address is mem at address 0x60 (reg 0) +run: storing 0x0000000d //: :(scenario and_mem_at_r32_with_r32) % Reg[0].i = 0x60; % Mem.at(0x60) = 0xff; % Reg[3].i = 0x0a0b0c0d; # op ModRM SIB displacement immediate 23 18 # and *EAX (reg 0) with EBX (reg 3) +run: and effective address with reg 3 +run: effective address is mem at address 0x60 (reg 0) +run: storing 0x0000000d :(before "End Single-Byte Opcodes") case 0x23: { // and r/m32 with r32 uint8_t modrm = next(); uint8_t arg1 = (modrm>>3)&0x7; trace(2, "run") << "and effective address with reg " << NUM(arg1) << end(); const int32_t* arg2 = effective_address(modrm); BINARY_BITWISE_OP(&, Reg[arg1].u, *arg2); break; } //:: or :(scenario or_r32_with_mem_at_r32) % Reg[0].i = 0x60; % Mem.at(0x60) = 0x0d; % Mem.at(0x61) = 0x0c; % Mem.at(0x62) = 0x0b; % Mem.at(0x63) = 0x0a; % Reg[3].i = 0xa0b0c0d0; # op ModRM SIB displacement immediate 09 18 # or EBX (reg 3) with *EAX (reg 0) +run: or reg 3 with effective address +run: effective address is mem at address 0x60 (reg 0) +run: storing 0xaabbccdd //: :(scenario or_mem_at_r32_with_r32) % Reg[0].i = 0x60; % Mem.at(0x60) = 0x0d; % Mem.at(0x61) = 0x0c; % Mem.at(0x62) = 0x0b; % Mem.at(0x63) = 0x0a; % Reg[3].i = 0xa0b0c0d0; # op ModRM SIB displacement immediate 0b 18 # or *EAX (reg 0) with EBX (reg 3) +run: or effective address with reg 3 +run: effective address is mem at address 0x60 (reg 0) +run: storing 0xaabbccdd :(before "End Single-Byte Opcodes") case 0x0b: { // or r/m32 with r32 uint8_t modrm = next(); uint8_t arg1 = (modrm>>3)&0x7; trace(2, "run") << "or effective address with reg " << NUM(arg1) << end(); const int32_t* arg2 = effective_address(modrm); BINARY_BITWISE_OP(|, Reg[arg1].u, *arg2); break; }