Index: xz/src/liblzma/api/lzma/vli.h |
=================================================================== |
--- xz/src/liblzma/api/lzma/vli.h (revision 0) |
+++ xz/src/liblzma/api/lzma/vli.h (revision 0) |
@@ -0,0 +1,167 @@ |
+/** |
+ * \file lzma/vli.h |
+ * \brief Variable-length integer handling |
+ * |
+ * In the .xz format, most integers are encoded in a variable-length |
+ * representation, which is sometimes called little endian base-128 encoding. |
+ * This saves space when smaller values are more likely than bigger values. |
+ * |
+ * The encoding scheme encodes seven bits to every byte, using minimum |
+ * number of bytes required to represent the given value. Encodings that use |
+ * non-minimum number of bytes are invalid, thus every integer has exactly |
+ * one encoded representation. The maximum number of bits in a VLI is 63, |
+ * thus the vli argument must be less than or equal to UINT64_MAX / 2. You |
+ * should use LZMA_VLI_MAX for clarity. |
+ */ |
+ |
+/* |
+ * Author: Lasse Collin |
+ * |
+ * This file has been put into the public domain. |
+ * You can do whatever you want with this file. |
+ * |
+ * See ../lzma.h for information about liblzma as a whole. |
+ */ |
+ |
+#ifndef LZMA_H_INTERNAL |
+# error Never include this file directly. Use <lzma.h> instead. |
+#endif |
+ |
+ |
+/** |
+ * \brief Maximum supported value of variable-length integer |
+ */ |
+#define LZMA_VLI_MAX (UINT64_MAX / 2) |
+ |
+/** |
+ * \brief VLI value to denote that the value is unknown |
+ */ |
+#define LZMA_VLI_UNKNOWN UINT64_MAX |
+ |
+/** |
+ * \brief Maximum supported length of variable length integers |
+ */ |
+#define LZMA_VLI_BYTES_MAX 9 |
+ |
+ |
+/** |
+ * \brief VLI constant suffix |
+ */ |
+#define LZMA_VLI_C(n) UINT64_C(n) |
+ |
+ |
+/** |
+ * \brief Variable-length integer type |
+ * |
+ * This will always be unsigned integer. Valid VLI values are in the range |
+ * [0, LZMA_VLI_MAX]. Unknown value is indicated with LZMA_VLI_UNKNOWN, |
+ * which is the maximum value of the underlaying integer type. |
+ * |
+ * In future, even if lzma_vli is defined to be something other than uint64_t, |
+ * it is guaranteed that 2 * LZMA_VLI_MAX will not overflow lzma_vli. |
+ * This simplifies integer overflow detection. |
+ */ |
+typedef uint64_t lzma_vli; |
+ |
+ |
+/** |
+ * \brief Simple macro to validate variable-length integer |
+ * |
+ * This is useful to test that application has given acceptable values |
+ * for example in the uncompressed_size and compressed_size variables. |
+ * |
+ * \return True if the integer is representable as VLI or if it |
+ * indicates unknown value. |
+ */ |
+#define lzma_vli_is_valid(vli) \ |
+ ((vli) <= LZMA_VLI_MAX || (vli) == LZMA_VLI_UNKNOWN) |
+ |
+ |
+/** |
+ * \brief Encode a variable-length integer |
+ * |
+ * This function has two modes: single-call and multi-call. Single-call mode |
+ * encodes the whole integer at once; it is an error if the output buffer is |
+ * too small. Multi-call mode saves the position in *vli_pos, and thus it is |
+ * possible to continue encoding if the buffer becomes full before the whole |
+ * integer has been encoded. |
+ * |
+ * \param vli Integer to be encoded |
+ * \param vli_pos How many VLI-encoded bytes have already been written |
+ * out. When starting to encode a new integer, *vli_pos |
+ * must be set to zero. To use single-call encoding, |
+ * set vli_pos to NULL. |
+ * \param out Beginning of the output buffer |
+ * \param out_pos The next byte will be written to out[*out_pos]. |
+ * \param out_size Size of the out buffer; the first byte into |
+ * which no data is written to is out[out_size]. |
+ * |
+ * \return Slightly different return values are used in multi-call and |
+ * single-call modes. |
+ * |
+ * Single-call (vli_pos == NULL): |
+ * - LZMA_OK: Integer successfully encoded. |
+ * - LZMA_PROG_ERROR: Arguments are not sane. This can be due |
+ * to too little output space; single-call mode doesn't use |
+ * LZMA_BUF_ERROR, since the application should have checked |
+ * the encoded size with lzma_vli_size(). |
+ * |
+ * Multi-call (vli_pos != NULL): |
+ * - LZMA_OK: So far all OK, but the integer is not |
+ * completely written out yet. |
+ * - LZMA_STREAM_END: Integer successfully encoded. |
+ * - LZMA_BUF_ERROR: No output space was provided. |
+ * - LZMA_PROG_ERROR: Arguments are not sane. |
+ */ |
+extern LZMA_API(lzma_ret) lzma_vli_encode(lzma_vli vli, size_t *vli_pos, |
+ uint8_t *out, size_t *out_pos, size_t out_size) lzma_nothrow; |
+ |
+ |
+/** |
+ * \brief Decode a variable-length integer |
+ * |
+ * Like lzma_vli_encode(), this function has single-call and multi-call modes. |
+ * |
+ * \param vli Pointer to decoded integer. The decoder will |
+ * initialize it to zero when *vli_pos == 0, so |
+ * application isn't required to initialize *vli. |
+ * \param vli_pos How many bytes have already been decoded. When |
+ * starting to decode a new integer, *vli_pos must |
+ * be initialized to zero. To use single-call decoding, |
+ * set this to NULL. |
+ * \param in Beginning of the input buffer |
+ * \param in_pos The next byte will be read from in[*in_pos]. |
+ * \param in_size Size of the input buffer; the first byte that |
+ * won't be read is in[in_size]. |
+ * |
+ * \return Slightly different return values are used in multi-call and |
+ * single-call modes. |
+ * |
+ * Single-call (vli_pos == NULL): |
+ * - LZMA_OK: Integer successfully decoded. |
+ * - LZMA_DATA_ERROR: Integer is corrupt. This includes hitting |
+ * the end of the input buffer before the whole integer was |
+ * decoded; providing no input at all will use LZMA_DATA_ERROR. |
+ * - LZMA_PROG_ERROR: Arguments are not sane. |
+ * |
+ * Multi-call (vli_pos != NULL): |
+ * - LZMA_OK: So far all OK, but the integer is not |
+ * completely decoded yet. |
+ * - LZMA_STREAM_END: Integer successfully decoded. |
+ * - LZMA_DATA_ERROR: Integer is corrupt. |
+ * - LZMA_BUF_ERROR: No input was provided. |
+ * - LZMA_PROG_ERROR: Arguments are not sane. |
+ */ |
+extern LZMA_API(lzma_ret) lzma_vli_decode(lzma_vli *vli, size_t *vli_pos, |
+ const uint8_t *in, size_t *in_pos, size_t in_size) |
+ lzma_nothrow; |
+ |
+ |
+/** |
+ * \brief Get the number of bytes required to encode a VLI |
+ * |
+ * \return Number of bytes on success (1-9). If vli isn't valid, |
+ * zero is returned. |
+ */ |
+extern LZMA_API(uint32_t) lzma_vli_size(lzma_vli vli) |
+ lzma_nothrow lzma_attr_pure; |
Property changes on: xz/src/liblzma/api/lzma/vli.h |
___________________________________________________________________ |
Added: svn:eol-style |
+ LF |