* Decode a memory fragment which is encoded with 'format80'. * @param dest The place the decoded fragment will be loaded. * @param source The encoded fragment. * @param destLength The length of the destination buffer. * @return The length of decoded data. */
| 14 | * @return The length of decoded data. |
| 15 | */ |
| 16 | uint16 Format80_Decode(uint8 *dest, const uint8 *source, uint16 destLength) |
| 17 | { |
| 18 | uint8 *start = dest; |
| 19 | uint8 *end = dest + destLength; |
| 20 | |
| 21 | while (dest != end) { |
| 22 | uint8 cmd; |
| 23 | uint16 size; |
| 24 | uint16 offset; |
| 25 | |
| 26 | cmd = *source++; |
| 27 | |
| 28 | if (cmd == 0x80) { |
| 29 | /* Exit */ |
| 30 | break; |
| 31 | |
| 32 | } else if ((cmd & 0x80) == 0) { |
| 33 | /* Short move, relative */ |
| 34 | size = (cmd >> 4) + 3; |
| 35 | if (size > end - dest) size = (uint16)(end - dest); |
| 36 | |
| 37 | offset = ((cmd & 0xF) << 8) + (*source++); |
| 38 | |
| 39 | /* This decoder assumes memcpy. As some platforms implement memcpy as memmove, this is much safer */ |
| 40 | for (; size > 0; size--) { *dest = *(dest - offset); dest++; } |
| 41 | |
| 42 | } else if (cmd == 0xFE) { |
| 43 | /* Long set */ |
| 44 | size = *source++; |
| 45 | size += (*source++) << 8; |
| 46 | if (size > end - dest) size = (uint16)(end - dest); |
| 47 | |
| 48 | memset(dest, (*source++), size); |
| 49 | dest += size; |
| 50 | |
| 51 | } else if (cmd == 0xFF) { |
| 52 | /* Long move, absolute */ |
| 53 | size = *source++; |
| 54 | size += (*source++) << 8; |
| 55 | if (size > end - dest) size = (uint16)(end - dest); |
| 56 | |
| 57 | offset = *source++; |
| 58 | offset += (*source++) << 8; |
| 59 | |
| 60 | /* This decoder assumes memcpy. As some platforms implement memcpy as memmove, this is much safer */ |
| 61 | for (; size > 0; size--) *dest++ = start[offset++]; |
| 62 | |
| 63 | } else if ((cmd & 0x40) != 0) { |
| 64 | /* Short move, absolute */ |
| 65 | size = (cmd & 0x3F) + 3; |
| 66 | if (size > end - dest) size = (uint16)(end - dest); |
| 67 | |
| 68 | offset = *source++; |
| 69 | offset += (*source++) << 8; |
| 70 | |
| 71 | /* This decoder assumes memcpy. As some platforms implement memcpy as memmove, this is much safer */ |
| 72 | for (; size > 0; size--) *dest++ = start[offset++]; |
| 73 |
no outgoing calls
no test coverage detected