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author | Kartik Agaram <vc@akkartik.com> | 2018-08-03 23:42:20 -0700 |
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committer | Kartik Agaram <vc@akkartik.com> | 2018-08-03 23:42:37 -0700 |
commit | a066ad7ed7a64ff204d9381d701cc94e83d42f79 (patch) | |
tree | e5258558e6038b6321c468dc145e33c92cb78646 /subx/015index_addressing.cc | |
parent | 96a09ee9f9017294313cfb6daf04864ace78ba75 (diff) | |
download | mu-a066ad7ed7a64ff204d9381d701cc94e83d42f79.tar.gz |
4469
Diffstat (limited to 'subx/015index_addressing.cc')
-rw-r--r-- | subx/015index_addressing.cc | 125 |
1 files changed, 0 insertions, 125 deletions
diff --git a/subx/015index_addressing.cc b/subx/015index_addressing.cc deleted file mode 100644 index b1b7e563..00000000 --- a/subx/015index_addressing.cc +++ /dev/null @@ -1,125 +0,0 @@ -//: operating on memory at the address provided by some register plus optional scale and offset - -:(scenario add_r32_to_mem_at_r32_with_sib) -% Reg[EBX].i = 0x10; -% Reg[EAX].i = 0x60; -== 0x1 # code segment -# op ModR/M SIB displacement immediate - 01 1c 20 # add EBX to *EAX -# ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB) -# SIB in binary: 00 (scale 1) 100 (no index) 000 (base EAX) -== 0x60 # data segment -01 00 00 00 # 1 -+run: add EBX to r/m32 -+run: effective address is initially 0x60 (EAX) -+run: effective address is 0x60 -+run: storing 0x00000011 - -:(before "End Mod 0 Special-cases(addr)") -case 4: // exception: mod 0b00 rm 0b100 => incoming SIB (scale-index-base) byte - addr = effective_address_from_sib(mod); - break; -:(code) -uint32_t effective_address_from_sib(uint8_t mod) { - uint8_t sib = next(); - uint8_t base = sib&0x7; - uint32_t addr = 0; - if (base != EBP || mod != 0) { - addr = Reg[base].u; - trace(90, "run") << "effective address is initially 0x" << std::hex << addr << " (" << rname(base) << ")" << end(); - } - else { - // base == EBP && mod == 0 - addr = imm32(); // ignore base - trace(90, "run") << "effective address is initially 0x" << std::hex << addr << " (disp32)" << end(); - } - uint8_t index = (sib>>3)&0x7; - if (index == ESP) { - // ignore index and scale - trace(90, "run") << "effective address is 0x" << std::hex << addr << end(); - } - else { - uint8_t scale = (1 << (sib>>6)); - addr += Reg[index].i*scale; // treat index register as signed. Maybe base as well? But we'll always ensure it's non-negative. - trace(90, "run") << "effective address is 0x" << std::hex << addr << " (after adding " << rname(index) << "*" << NUM(scale) << ")" << end(); - } - return addr; -} - -:(scenario add_r32_to_mem_at_base_r32_index_r32) -% Reg[EBX].i = 0x10; // source -% Reg[EAX].i = 0x5e; // dest base -% Reg[ECX].i = 0x2; // dest index -== 0x1 # code segment -# op ModR/M SIB displacement immediate - 01 1c 08 # add EBX to *(EAX+ECX) -# ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB) -# SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX) -== 0x60 # data segment -01 00 00 00 # 1 -+run: add EBX to r/m32 -+run: effective address is initially 0x5e (EAX) -+run: effective address is 0x60 (after adding ECX*1) -+run: storing 0x00000011 - -:(scenario add_r32_to_mem_at_displacement_using_sib) -% Reg[EBX].i = 0x10; // source -== 0x1 # code segment -# op ModR/M SIB displacement immediate - 01 1c 25 60 00 00 00 # add EBX to *0x60 -# ModR/M in binary: 00 (indirect mode) 011 (src EBX) 100 (dest in SIB) -# SIB in binary: 00 (scale 1) 100 (no index) 101 (not EBP but disp32) -== 0x60 # data segment -01 00 00 00 # 1 -+run: add EBX to r/m32 -+run: effective address is initially 0x60 (disp32) -+run: effective address is 0x60 -+run: storing 0x00000011 - -//: - -:(scenario add_r32_to_mem_at_base_r32_index_r32_plus_disp8) -% Reg[EBX].i = 0x10; // source -% Reg[EAX].i = 0x59; // dest base -% Reg[ECX].i = 0x5; // dest index -== 0x1 # code segment -# op ModR/M SIB displacement immediate - 01 5c 08 02 # add EBX to *(EAX+ECX+2) -# ModR/M in binary: 01 (indirect+disp8 mode) 011 (src EBX) 100 (dest in SIB) -# SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX) -== 0x60 # data segment -01 00 00 00 # 1 -+run: add EBX to r/m32 -+run: effective address is initially 0x59 (EAX) -+run: effective address is 0x5e (after adding ECX*1) -+run: effective address is 0x60 (after adding disp8) -+run: storing 0x00000011 - -:(before "End Mod 1 Special-cases(addr)") -case 4: // exception: mod 0b01 rm 0b100 => incoming SIB (scale-index-base) byte - addr = effective_address_from_sib(mod); - break; - -//: - -:(scenario add_r32_to_mem_at_base_r32_index_r32_plus_disp32) -% Reg[EBX].i = 0x10; // source -% Reg[EAX].i = 0x59; // dest base -% Reg[ECX].i = 0x5; // dest index -== 0x1 # code segment -# op ModR/M SIB displacement immediate - 01 9c 08 02 00 00 00 # add EBX to *(EAX+ECX+2) -# ModR/M in binary: 10 (indirect+disp32 mode) 011 (src EBX) 100 (dest in SIB) -# SIB in binary: 00 (scale 1) 001 (index ECX) 000 (base EAX) -== 0x60 # data segment -01 00 00 00 # 1 -+run: add EBX to r/m32 -+run: effective address is initially 0x59 (EAX) -+run: effective address is 0x5e (after adding ECX*1) -+run: effective address is 0x60 (after adding disp32) -+run: storing 0x00000011 - -:(before "End Mod 2 Special-cases(addr)") -case 4: // exception: mod 0b10 rm 0b100 => incoming SIB (scale-index-base) byte - addr = effective_address_from_sib(mod); - break; |