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#include "codes.h"
#include <exception>
#include <unordered_map>
using namespace std::string_literals;
// REX prefix: 0b0100WRXB
std::vector<uint8_t> REX(const std::string& s) {
uint8_t result{0b01000000};
if (s == "W")
result |= 0b00001000;
if (s == "R")
result |= 0b00000100;
if (s == "X")
result |= 0b00000010;
if (s == "B")
result |= 0b00000001;
return { result };
}
namespace {
std::unordered_map<std::string, size_t> IndexOfRegister{
{"al", 0}, {"ah", 4},
{"bl", 3}, {"bh", 7},
{"cl", 1}, {"ch", 5},
{"dl", 2}, {"dh", 6},
{"ax", 0}, {"sp", 4},
{"bx", 3}, {"bp", 7},
{"cx", 1}, {"si", 5},
{"dx", 2}, {"di", 6},
{"eax", 0}, {"esp", 4},
{"ebx", 3}, {"ebp", 7},
{"ecx", 1}, {"esi", 5},
{"edx", 2}, {"edi", 6},
};
}
// Manual, page 530
// Reg + Reg/Memory
uint8_t ModRM(const std::string& reg, const std::string& rm) {
// TODO: extend
uint8_t result{0b11000000};
auto index1{ IndexOfRegister.find(reg) };
if (index1 == IndexOfRegister.end())
throw std::runtime_error("Unknown register for arg1: "s + reg);
result |= (index1->second << 3);
auto index2{ IndexOfRegister.find(rm) };
if (index2 == IndexOfRegister.end())
throw std::runtime_error("Unknown register for arg2: "s + rm);
result |= index2->second;
return result;
}
#if 0
prefixes{
"lock", 0xf0,
// branch hint
0x2e, "branch not taken"
0x3e, "branch taken"
0x66, "operand size override" // switch between 16 and 32 bit operands
0x67, "address size override" // switch between 16 and 32 bit addresses
};
};
#endif
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