Initial commit: try make binaries

wozmon.cc

@@ -0,0 +1,151 @@
+#include <cstdint>
+
+namespace {
+
+uint8_t getc() {
+    register uint8_t c asm ("al");
+    asm volatile (
+            "mov $0x00, %%ah\n"
+            "int $0x16\n"
+            : "=r" (c)
+            );
+    return c;
+}
+
+void putc(uint8_t c) {
+    asm volatile (
+            "mov %0, %%al\n"
+            "mov $0x0e, %%ah\n"
+            "int $0x10\n"
+            :: "r" (c)
+            );
+}
+
+void Jump(uint32_t addr) {
+    auto jump = reinterpret_cast<void (*)()>(addr);
+    jump();
+}
+
+constexpr uint8_t kBackspace = 0x7f;
+constexpr uint8_t kOtherBackspace = 0x08;
+
+uint8_t ReadHexNibble(uint8_t c) {
+    // lowercase only
+    if (c <= '9') {
+        return c - '0';
+    }
+    return 10 + (c - 'a');
+}
+
+uint32_t ReadHex(const char* buf) {
+    uint32_t out = 0;
+    while (*buf == ' ') {
+        buf++;
+    }
+    for (int i = 0; i < 8; i++) {
+        uint8_t c = ReadHexNibble(*buf);
+        if (c > 0xf) {
+            break;
+        }
+        out = (out << 4) + c;
+        buf++;
+    }
+
+    return out;
+}
+
+void WriteHexNibble(uint8_t c) {
+    if (c > 9) {
+        putc('a' + c - 10);
+    } else {
+        putc('0' + c);
+    }
+}
+
+void WriteUint32(uint32_t a) {
+    for (int i = 0; i < 8; i++) {
+        WriteHexNibble((a >> 28) & 0xf);
+        a <<= 4;
+    }
+}
+
+void WriteUint8(uint8_t a) {
+    WriteHexNibble(a >> 4);
+    WriteHexNibble(a & 0xf);
+}
+
+void Dump(uint32_t addr, int count) {
+    for (int i = 0; i < count; i++) {
+        putc(' ');
+        WriteUint8(*reinterpret_cast<uint8_t*>(addr + i));
+    }
+}
+
+void DumpHex(uint32_t addr) {
+    addr &= 0xfffffffc;
+    WriteUint32(addr);
+    putc(':');
+    Dump(addr, 4);
+    putc('\r');
+    putc('\n');
+}
+
+int FindChar(const char* buf, uint8_t c) {
+    int found = 0;
+    while (*buf) {
+        if (*buf == c) {
+            return found;
+        }
+        found++;
+        buf++;
+    }
+    return -1;
+}
+
+void wozmon() {
+    uint32_t cur_addr = 0;
+    uint32_t cur_data = 0;
+
+    char inbuf[64] = {};
+    char* inptr = inbuf;
+
+    while (1) {
+        uint8_t c = getc();
+        putc(c);  // echo
+        if (c == '\r') {
+            *inptr = 0;
+            if (inptr == inbuf) {
+                cur_addr += 4;
+            } else if (FindChar(inbuf, 'r') >= 0) {
+                Jump(cur_addr);
+            } else {
+                cur_addr = ReadHex(inbuf);
+                putc('\n');
+            }
+            DumpHex(cur_addr);
+            int assigned = FindChar(inbuf, ':');
+            if (assigned >= 0) {
+                cur_data = ReadHex(inbuf + assigned + 1);
+                *(reinterpret_cast<uint32_t*>(cur_addr)) = cur_data;
+            }
+            inptr = inbuf;
+        } else if (c == kBackspace) {
+            inptr--;
+            if (inptr < inbuf) {
+                inptr = inbuf;
+                continue;
+            }
+            putc(kOtherBackspace);
+            putc(' ');
+            putc(kOtherBackspace);
+        } else {
+            *inptr++ = c;
+        }
+    }
+}
+
+}  // namespace
+
+int main() {
+    wozmon();
+}