diff options
| -rw-r--r-- | subx/010core.cc | 71 |
1 files changed, 53 insertions, 18 deletions
diff --git a/subx/010core.cc b/subx/010core.cc index afbffb9e..cbdd4ad0 100644 --- a/subx/010core.cc +++ b/subx/010core.cc @@ -72,7 +72,8 @@ End_of_program = 0; # opcode ModRM SIB displacement immediate # instruction mod, reg, R/M bits scale, index, base # 1-3 bytes 0/1 byte 0/1 byte 0/1/2/4 bytes 0/1/2/4 bytes - 0x05 0a 0b 0c 0d # add 0x0d0c0b0a to EAX + 05 0a 0b 0c 0d # add 0x0d0c0b0a to EAX +# All hex bytes must be exactly 2 characters each. No '0x' prefixes. +load: 1 -> 05 +load: 2 -> 0a +load: 3 -> 0b @@ -139,29 +140,63 @@ void run_one_instruction() { void load_program(const string& text_bytes) { uint32_t addr = 1; - // we'll use C's 'strtol` to parse ASCII hex bytes - // strtol needs a char*, so we grab the buffer backing the string object - char* curr = const_cast<char*>(&text_bytes[0]); // non-portable, but blessed by Herb Sutter (http://herbsutter.com/2008/04/07/cringe-not-vectors-are-guaranteed-to-be-contiguous/#comment-483) - char* max = curr + strlen(curr); - while (curr < max) { - // skip whitespace - while (*curr == ' ' || *curr == '\n') ++curr; - // skip comments - if (*curr == '#') { - while (*curr != '\n') { - ++curr; - if (curr >= max) break; - } - ++curr; - continue; + istringstream in(text_bytes); + in >> std::noskipws; + while (has_data(in)) { + char c1 = next_hex_byte(in); + if (c1 == '\0') break; + if (!has_data(in)) { + raise << "input program truncated mid-byte\n" << end(); + return; + } + char c2 = next_hex_byte(in); + if (c2 == '\0') { + raise << "input program truncated mid-byte\n" << end(); + return; } - put(Memory, addr, strtol(curr, &curr, /*hex*/16)); - trace(99, "load") << addr << " -> " << HEXBYTE << static_cast<unsigned int>(get_or_insert(Memory, addr)) << end(); // ugly that iostream doesn't print uint8_t as an integer + put(Memory, addr, to_byte(c1, c2)); + trace(99, "load") << addr << " -> " << HEXBYTE << static_cast<int>(get_or_insert(Memory, addr)) << end(); // ugly that iostream doesn't print uint8_t as an integer addr++; } End_of_program = addr; } +char next_hex_byte(istream& in) { + while (has_data(in)) { + char c = '\0'; + in >> c; + if (c == ' ' || c == '\n') continue; + while (c == '#') { + while (has_data(in)) { + in >> c; + if (c == '\n') { + in >> c; + break; + } + } + } + if (c >= '0' && c <= '9') return c; + else if (c >= 'a' && c <= 'f') return c; + else if (c >= 'A' && c <= 'F') return tolower(c); + // disallow any non-hex characters, including a '0x' prefix + if (!isspace(c)) { + raise << "invalid non-hex character '" << c << "'\n" << end(); + break; + } + } + return '\0'; +} + +uint8_t to_byte(char hex_byte1, char hex_byte2) { + return to_hex_num(hex_byte1)*16 + to_hex_num(hex_byte2); +} +uint8_t to_hex_num(char c) { + if (c >= '0' && c <= '9') return c - '0'; + if (c >= 'a' && c <= 'f') return c - 'a' + 10; + assert(false); + return 0; +} + uint8_t next() { return get_or_insert(Memory, EIP++); } |