| Simon Glass | fa8974d | 2016-07-04 11:58:08 -0600 | [diff] [blame] | 1 | #!/usr/bin/python |
| 2 | # |
| 3 | # Copyright (C) 2016 Google, Inc |
| 4 | # Written by Simon Glass <sjg@chromium.org> |
| 5 | # |
| 6 | # SPDX-License-Identifier: GPL-2.0+ |
| 7 | # |
| 8 | |
| 9 | import struct |
| 10 | |
| 11 | # A list of types we support |
| 12 | (TYPE_BYTE, TYPE_INT, TYPE_STRING, TYPE_BOOL) = range(4) |
| 13 | |
| 14 | def BytesToValue(bytes): |
| 15 | """Converts a string of bytes into a type and value |
| 16 | |
| 17 | Args: |
| 18 | A string containing bytes |
| 19 | |
| 20 | Return: |
| 21 | A tuple: |
| 22 | Type of data |
| 23 | Data, either a single element or a list of elements. Each element |
| 24 | is one of: |
| 25 | TYPE_STRING: string value from the property |
| 26 | TYPE_INT: a byte-swapped integer stored as a 4-byte string |
| 27 | TYPE_BYTE: a byte stored as a single-byte string |
| 28 | """ |
| 29 | size = len(bytes) |
| 30 | strings = bytes.split('\0') |
| 31 | is_string = True |
| 32 | count = len(strings) - 1 |
| 33 | if count > 0 and not strings[-1]: |
| 34 | for string in strings[:-1]: |
| 35 | if not string: |
| 36 | is_string = False |
| 37 | break |
| 38 | for ch in string: |
| 39 | if ch < ' ' or ch > '~': |
| 40 | is_string = False |
| 41 | break |
| 42 | else: |
| 43 | is_string = False |
| 44 | if is_string: |
| 45 | if count == 1: |
| 46 | return TYPE_STRING, strings[0] |
| 47 | else: |
| 48 | return TYPE_STRING, strings[:-1] |
| 49 | if size % 4: |
| 50 | if size == 1: |
| 51 | return TYPE_BYTE, bytes[0] |
| 52 | else: |
| 53 | return TYPE_BYTE, list(bytes) |
| 54 | val = [] |
| 55 | for i in range(0, size, 4): |
| 56 | val.append(bytes[i:i + 4]) |
| 57 | if size == 4: |
| 58 | return TYPE_INT, val[0] |
| 59 | else: |
| 60 | return TYPE_INT, val |
| 61 | |
| 62 | def GetEmpty(type): |
| 63 | """Get an empty / zero value of the given type |
| 64 | |
| 65 | Returns: |
| 66 | A single value of the given type |
| 67 | """ |
| 68 | if type == TYPE_BYTE: |
| 69 | return chr(0) |
| 70 | elif type == TYPE_INT: |
| 71 | return struct.pack('<I', 0); |
| 72 | elif type == TYPE_STRING: |
| 73 | return '' |
| 74 | else: |
| 75 | return True |
| 76 | |
| 77 | def fdt32_to_cpu(val): |
| 78 | """Convert a device tree cell to an integer |
| 79 | |
| 80 | Args: |
| 81 | Value to convert (4-character string representing the cell value) |
| 82 | |
| 83 | Return: |
| 84 | A native-endian integer value |
| 85 | """ |
| 86 | return struct.unpack(">I", val)[0] |