1 files changed, 54 insertions, 0 deletions
diff --git a/common.h b/common.h
new file mode 100644
index 0000000..7616b67
--- /dev/null
+++ b/common.h
@@ -0,0 +1,54 @@
+#pragma once
+#include <stdint.h>
+
+typedef uint8_t byte;
+
+// Limit file size to something reasonable.
+#define MAX_FILE_SIZE 2000000000
+
+// Decode LEB128 values, enforcing the specified signedness and maximum range.
+// The argument {ptr} will be advanced to point after the decoded value.
+// If an error occurs (e.g. unterminated LEB, invalid value), {ptr} will be set to
+// NULL.
+int32_t  decode_i32leb(const byte* ptr, const byte* limit, ssize_t* len);
+uint32_t decode_u32leb(const byte* ptr, const byte* limit, ssize_t* len);
+int64_t  decode_i64leb(const byte* ptr, const byte* limit, ssize_t* len);
+uint64_t decode_u64leb(const byte* ptr, const byte* limit, ssize_t* len);
+
+// Decode fixed-size integer values.
+uint32_t decode_u32(const byte* ptr, const byte* limit, ssize_t* len);
+
+// Load a file into memory, initializing pointers to the start and end of
+// the memory range containing the data. Returns < 0 on failure.
+ssize_t load_file(const char* path, byte** start, byte** end);
+
+// Unload a file previously loaded into memory using {load_file}.
+ssize_t unload_file(byte** start, byte** end);
+
+// The global trace flag.
+extern int g_trace;
+extern int g_disassemble;
+extern int g_indent;
+
+// Helper macros to trace and to print errors.
+#define TRACE(...) do { if(g_trace) fprintf(stderr, __VA_ARGS__); } while(0)
+#define TRACE_INDENT(...) do { for (int i = 0; i < g_indent; i++) fprintf(stderr, "  "); TRACE(__VA_ARGS__); } while(0)
+#define DISASS(...) do { if(g_disassemble) fprintf(stderr, __VA_ARGS__); } while(0)
+#define ERR(...) fprintf(stderr, __VA_ARGS__)
+
+// A helper struct that keeps track of the start and the current pointer of
+// a buffer.
+typedef struct {
+  const byte* start;
+  const byte* ptr;
+  const byte* end;
+} buffer_t;
+
+// Read an unsigned 32-bit LEB, advancing the {ptr} in the buffer.
+uint32_t read_u32leb(buffer_t* buf);
+
+// Read a signed 32-bit LEB, advancing the {ptr} in the buffer.
+int32_t read_i32leb(buffer_t* buf);
+
+// Read an unsigned 8-bit byte, advancing the {ptr} in the buffer.
+uint32_t read_u8(buffer_t* buf);