first commitmaster

1 files changed, 117 insertions, 0 deletions

diff --git a/bin/leb128 b/bin/leb128
new file mode 100755
index 0000000..02a11e5
--- /dev/null
+++ b/bin/leb128
@@ -0,0 +1,117 @@
+#!/bin/python3
+
+import argparse
+import code
+import signal
+import sys
+
+
+def SigHandler_SIGINT(signum, frame):
+    print()
+    sys.exit(0)
+
+
+def devibytes(val):
+    ret = []
+    for byte in val.split(","):
+        ret.append(int(byte, 16))
+    return bytes(ret)
+
+
+def LEB128UnsignedDecode(bytelist):
+    result = 0
+    shift = 0
+    for byte in bytelist:
+        result |= (byte & 0x7f) << shift
+        if (byte & 0x80) == 0:
+            break
+        shift += 7
+    return(result)
+
+
+def LEB128SignedDecode(bytelist):
+    result = 0
+    shift = 0
+    for byte in bytelist:
+        result |= (byte & 0x7f) << shift
+        last_byte = byte
+        shift += 7
+        if (byte & 0x80) == 0:
+            break
+    if last_byte & 0x40:
+        result |= - (1 << shift)
+    return(result)
+
+
+def LEB128UnsignedEncode(int_val):
+    if int_val < 0:
+        raise Exception("value must not be negative")
+    elif int_val == 0:
+        return bytes([0])
+    byte_array = bytearray()
+    while int_val:
+        byte = int_val & 0x7f
+        byte_array.append(byte | 0x80)
+        int_val >>= 7
+    byte_array[-1] ^= 0x80
+    return(byte_array)
+
+
+def LEB128SignedEncode(int_val):
+    byte_array = bytearray()
+    while True:
+        byte = int_val & 0x7f
+        byte_array.append(byte | 0x80)
+        int_val >>= 7
+        if (int_val == 0 and byte & 0x40 == 0) or (int_val == -1 and byte & 0x40):
+            byte_array[-1] ^= 0x80
+            break
+    return(byte_array)
+
+
+class Argparser(object):
+    def __init__(self):
+        parser = argparse.ArgumentParser()
+        parser.add_argument("--se", type=int, help="leb128 signed encode")
+        parser.add_argument("--ue", type=int, help="leb128 unsigned encode")
+        parser.add_argument(
+            "--sd", type=devibytes, help="leb128 signed decode. pass a string like ef1289.")
+        parser.add_argument(
+            "--ud", type=devibytes, help="leb128 unsigned decode. pass a string like ef1290")
+        self.args = parser.parse_args()
+
+# write code here
+
+
+def premain():
+    signal.signal(signal.SIGINT, SigHandler_SIGINT)
+    argparser = Argparser()
+    # here
+    if argparser.args.se:
+        res = LEB128SignedEncode(argparser.args.se)
+        for byte in res:
+            print(format(byte, "02x"), end=" ")
+        print()
+    if argparser.args.ue:
+        res = LEB128UnsignedEncode(argparser.args.ue)
+        for byte in res:
+            print(format(byte, "02x"), end=" ")
+        print()
+    if argparser.args.sd:
+        print(LEB128SignedDecode(argparser.args.sd))
+    if argparser.args.ud:
+        print(LEB128UnsignedDecode(argparser.args.ud))
+
+
+def main():
+    try:
+        premain()
+    except:
+        variables = globals().copy()
+        variables.update(locals())
+        shell = code.InteractiveConsole(variables)
+        shell.interact(banner="LEB128 DEBUG REPL")
+
+
+if __name__ == "__main__":
+    main()