152 lines
2.9 KiB
C++
152 lines
2.9 KiB
C++
#include <cstdint>
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namespace {
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uint8_t getc() {
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register uint8_t c asm ("al");
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asm volatile (
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"mov $0x00, %%ah\n"
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"int $0x16\n"
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: "=r" (c)
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);
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return c;
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}
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void putc(uint8_t c) {
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asm volatile (
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"mov %0, %%al\n"
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"mov $0x0e, %%ah\n"
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"int $0x10\n"
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:: "r" (c)
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);
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}
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void Jump(uint32_t addr) {
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auto jump = reinterpret_cast<void (*)()>(addr);
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jump();
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}
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constexpr uint8_t kBackspace = 0x7f;
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constexpr uint8_t kOtherBackspace = 0x08;
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uint8_t ReadHexNibble(uint8_t c) {
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// lowercase only
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if (c <= '9') {
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return c - '0';
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}
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return 10 + (c - 'a');
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}
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uint32_t ReadHex(const char* buf) {
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uint32_t out = 0;
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while (*buf == ' ') {
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buf++;
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}
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for (int i = 0; i < 8; i++) {
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uint8_t c = ReadHexNibble(*buf);
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if (c > 0xf) {
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break;
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}
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out = (out << 4) + c;
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buf++;
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}
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return out;
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}
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void WriteHexNibble(uint8_t c) {
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if (c > 9) {
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putc('a' + c - 10);
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} else {
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putc('0' + c);
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}
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}
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void WriteUint32(uint32_t a) {
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for (int i = 0; i < 8; i++) {
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WriteHexNibble((a >> 28) & 0xf);
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a <<= 4;
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}
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}
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void WriteUint8(uint8_t a) {
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WriteHexNibble(a >> 4);
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WriteHexNibble(a & 0xf);
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}
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void Dump(uint32_t addr, int count) {
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for (int i = 0; i < count; i++) {
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putc(' ');
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WriteUint8(*reinterpret_cast<uint8_t*>(addr + i));
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}
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}
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void DumpHex(uint32_t addr) {
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addr &= 0xfffffffc;
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WriteUint32(addr);
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putc(':');
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Dump(addr, 4);
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putc('\r');
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putc('\n');
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}
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int FindChar(const char* buf, uint8_t c) {
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int found = 0;
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while (*buf) {
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if (*buf == c) {
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return found;
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}
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found++;
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buf++;
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}
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return -1;
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}
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void wozmon() {
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uint32_t cur_addr = 0;
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uint32_t cur_data = 0;
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char inbuf[64] = {};
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char* inptr = inbuf;
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while (1) {
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uint8_t c = getc();
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putc(c); // echo
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if (c == '\r') {
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*inptr = 0;
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if (inptr == inbuf) {
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cur_addr += 4;
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} else if (FindChar(inbuf, 'r') >= 0) {
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Jump(cur_addr);
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} else {
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cur_addr = ReadHex(inbuf);
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putc('\n');
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}
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DumpHex(cur_addr);
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int assigned = FindChar(inbuf, ':');
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if (assigned >= 0) {
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cur_data = ReadHex(inbuf + assigned + 1);
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*(reinterpret_cast<uint32_t*>(cur_addr)) = cur_data;
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}
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inptr = inbuf;
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} else if (c == kBackspace) {
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inptr--;
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if (inptr < inbuf) {
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inptr = inbuf;
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continue;
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}
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putc(kOtherBackspace);
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putc(' ');
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putc(kOtherBackspace);
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} else {
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*inptr++ = c;
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}
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}
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}
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} // namespace
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int main() {
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wozmon();
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}
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