renamed scrambler -> ascii85

1 files changed, 0 insertions, 353 deletions

diff --git a/scrambler.c b/scrambler.c
deleted file mode 100644
index 340a34a..0000000
--- a/scrambler.c
+++ /dev/null
@@ -1,353 +0,0 @@
-/** @file ascii85.c
- *
- * @brief Ascii85 encoder and decoder
- *
- * @par
- * @copyright Copyright © 2017 Doug Currie, Londonderry, NH, USA. All rights reserved.
- * 
- * @par
- * Permission is hereby granted, free of charge, to any person obtaining a copy of this software 
- * and associated documentation files (the "Software"), to deal in the Software without 
- * restriction, including without limitation the rights to use, copy, modify, merge, publish, 
- * distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the 
- * Software is furnished to do so, subject to the following conditions:
- * 
- * The above copyright notice and this permission notice shall be included in all copies or 
- * substantial portions of the Software.
- * 
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING 
- * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
- * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, 
- * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-**/
-
-/* from: https://github.com/dcurrie/ascii85 */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdint.h>
-#include <stdbool.h>
-
-enum ascii85_errs_e
-{
-    ascii85_err_out_buf_too_small = -255,
-    ascii85_err_in_buf_too_large,
-    ascii85_err_bad_decode_char,
-    ascii85_err_decode_overflow
-};
-
-int32_t encode_ascii85 (const uint8_t *inp, int32_t in_length, char *outp, int32_t out_max_length);
-
-int32_t decode_ascii85 (const char *inp, int32_t in_length, uint8_t *outp, int32_t out_max_length);
-
-// From Wikipedia re: Ascii85 length...
-// Adobe adopted the basic btoa encoding, but with slight changes, and gave it the name Ascii85.
-// The characters used are the ASCII characters 33 (!) through 117 (u) inclusive (to represent
-// the base-85 digits 0 through 84), together with the letter z (as a special case to represent
-// a 32-bit 0 value), and white space is ignored. Adobe uses the delimiter "~>" to mark the end
-// of an Ascii85-encoded string, and represents the length by truncating the final group: If the
-// last block of source bytes contains fewer than 4 bytes, the block is padded with up to three
-// null bytes before encoding. After encoding, as many bytes as were added as padding are
-// removed from the end of the output.
-// The reverse is applied when decoding: The last block is padded to 5 bytes with the Ascii85
-// character "u", and as many bytes as were added as padding are omitted from the end of the
-// output (see example).
-// NOTE: The padding is not arbitrary. Converting from binary to base 64 only regroups bits and
-// does not change them or their order (a high bit in binary does not affect the low bits in the
-// base64 representation). In converting a binary number to base85 (85 is not a power of two)
-// high bits do affect the low order base85 digits and conversely. Padding the binary low (with
-// zero bits) while encoding and padding the base85 value high (with 'u's) in decoding assures
-// that the high order bits are preserved (the zero padding in the binary gives enough room so
-// that a small addition is trapped and there is no "carry" to the high bits).
-
-// NOTE: ths implementation does not ignore white space!
-//
-// The motivation for this implementation is as a binary message wrapper for serial
-// communication; in that application, white space is used for message framing.
-
-static const uint8_t base_char = 33u; // '!' -- note that (85 + 33) < 128
-
-static const int32_t ascii85_in_length_max = 65536;
-static const bool ascii85_check_decode_chars = true;
-#define ENDECODE_NUL_AS_Z 1
-
-#if 0
-static inline bool ascii85_char_ok (uint8_t c)
-{
-    return ((c >= 33u) && (c <= 117u));
-}
-#endif
-
-static inline bool ascii85_char_ng (uint8_t c)
-{
-    return ((c < 33u) || (c > 117u));
-}
-
-/*!
- * @brief encode_ascii85: encode binary input into Ascii85
- * @param[in] inp pointer to a buffer of unsigned bytes 
- * @param[in] in_length the number of bytes at inp to encode
- * @param[in] outp pointer to a buffer for the encoded data as c-string
- * @param[in] out_max_length available space at outp in bytes; must be >= 5 * ceiling(in_length/4)
- * @return number of bytes in the encoded value at outp if non-negative; error code from
- * ascii85_errs_e if negative
- * @par Possible errors include: ascii85_err_in_buf_too_large, ascii85_err_out_buf_too_small
- */
-int32_t encode_ascii85 (const uint8_t *inp, int32_t in_length, char *outp, int32_t out_max_length)
-{
-    // Note that (in_length + 3) below may overflow, but this is inconsequental
-    // since ascii85_in_length_max is < (INT32_MAX - 3), and we check in_length before
-    // using the calculated out_length.
-    //
-    int32_t out_length = (((in_length + 3) / 4) * 5); // ceiling
-
-    if (in_length > ascii85_in_length_max)
-    {
-        out_length = (int32_t )ascii85_err_in_buf_too_large;
-    }
-    else if (out_length > out_max_length)
-    {
-        out_length = (int32_t )ascii85_err_out_buf_too_small;
-    }
-    else
-    {
-        int32_t in_rover = 0;
-
-        out_length = 0; // we know we can increment by 5 * ceiling(in_length/4)
-
-        while (in_rover < in_length)
-        {
-            uint32_t chunk;
-            int32_t chunk_len = in_length - in_rover;
-
-            if (chunk_len >= 4)
-            {
-                chunk  = (((uint32_t )inp[in_rover++]) << 24u);
-                chunk |= (((uint32_t )inp[in_rover++]) << 16u);
-                chunk |= (((uint32_t )inp[in_rover++]) <<  8u);
-                chunk |= (((uint32_t )inp[in_rover++])       );
-            }
-            else
-            {
-                chunk  =                           (((uint32_t )inp[in_rover++]) << 24u);
-                chunk |= ((in_rover < in_length) ? (((uint32_t )inp[in_rover++]) << 16u) : 0u);
-                chunk |= ((in_rover < in_length) ? (((uint32_t )inp[in_rover++]) <<  8u) : 0u);
-                chunk |= ((in_rover < in_length) ? (((uint32_t )inp[in_rover++])       ) : 0u);
-            }
-
-#ifdef ENDECODE_NUL_AS_Z
-            if (/*lint -e{506} -e{774}*/ (0u == chunk) && (chunk_len >= 4))
-            {
-                outp[out_length++] = (uint8_t )'z';
-            }
-            else
-#endif
-            {
-                outp[out_length + 4] = (chunk % 85u) + base_char;
-                chunk /= 85u;
-                outp[out_length + 3] = (chunk % 85u) + base_char;
-                chunk /= 85u;
-                outp[out_length + 2] = (chunk % 85u) + base_char;
-                chunk /= 85u;
-                outp[out_length + 1] = (chunk % 85u) + base_char;
-                chunk /= 85u;
-                outp[out_length    ] = (uint8_t )chunk + base_char;
-                // we don't need (chunk % 85u) on the last line since (((((2^32 - 1) / 85) / 85) / 85) / 85) = 82.278
-
-                if (chunk_len >= 4)
-                {
-                    out_length += 5;
-                }
-                else
-                {
-                    out_length += (chunk_len + 1); // see note above re: Ascii85 length
-                }
-            }
-        }
-    }
-
-    return out_length;
-}
-
-/*!
- * @brief decode_ascii85: decode Ascii85 input to binary output
- * @param[in] inp pointer to a buffer of Ascii85 encoded c-string
- * @param[in] in_length the number of bytes at inp to decode
- * @param[in] outp pointer to a buffer for the decoded data
- * @param[in] out_max_length available space at outp in bytes; must be >= 4 * ceiling(in_length/5)
- * @return number of bytes in the decoded value at outp if non-negative; error code from
- * ascii85_errs_e if negative
- * @par Possible errors include: ascii85_err_in_buf_too_large, ascii85_err_out_buf_too_small, 
- * ascii85_err_bad_decode_char, ascii85_err_decode_overflow
- */
-int32_t decode_ascii85 (const char *inp, int32_t in_length, uint8_t *outp, int32_t out_max_length)
-{
-    // Note that (in_length + 4) below may overflow, but this is inconsequental
-    // since ascii85_in_length_max is < (INT32_MAX - 4), and we check in_length before
-    // using the calculated out_length.
-    //
-    int32_t out_length = (((in_length + 4) / 5) * 4); // ceiling
-
-    if (in_length > ascii85_in_length_max)
-    {
-        out_length = (int32_t )ascii85_err_in_buf_too_large;
-    }
-    else if (out_length > out_max_length)
-    {
-        out_length = (int32_t )ascii85_err_out_buf_too_small;
-    }
-    else
-    {
-        int32_t in_rover = 0;
-
-        out_length = 0; // we know we can increment by 4 * ceiling(in_length/5)
-
-        while (in_rover < in_length)
-        {
-            uint32_t chunk;
-            int32_t chunk_len = in_length - in_rover;
-
-#ifdef ENDECODE_NUL_AS_Z
-            if (/*lint -e{506} -e{774}*/ ((uint8_t )'z' == inp[in_rover]))
-            {
-                in_rover += 1;
-                chunk = 0u;
-                chunk_len = 5; // to make out_length increment correct
-            }
-            else
-#endif
-            if (/*lint -e{506} -e{774}*/ascii85_check_decode_chars
-                    && (                       ascii85_char_ng(inp[in_rover    ])
-                        || ((chunk_len > 1) && ascii85_char_ng(inp[in_rover + 1]))
-                        || ((chunk_len > 2) && ascii85_char_ng(inp[in_rover + 2]))
-                        || ((chunk_len > 3) && ascii85_char_ng(inp[in_rover + 3]))
-                        || ((chunk_len > 4) && ascii85_char_ng(inp[in_rover + 4]))))
-            {
-                out_length = (int32_t )ascii85_err_bad_decode_char;
-                break; // leave while loop early to report error
-            }
-            else if (chunk_len >= 5)
-            {
-                chunk  = inp[in_rover++] - base_char;
-                chunk *= 85u; // max: 84 * 85 = 7,140
-                chunk += inp[in_rover++] - base_char;
-                chunk *= 85u; // max: (84 * 85 + 84) * 85 = 614,040
-                chunk += inp[in_rover++] - base_char;
-                chunk *= 85u; // max: (((84 * 85 + 84) * 85) + 84) * 85 = 52,200,540
-                chunk += inp[in_rover++] - base_char;
-                // max: (((((84 * 85 + 84) * 85) + 84) * 85) + 84) * 85 = 4,437,053,040 oops! 0x108780E70
-                if (chunk > (UINT32_MAX / 85u))
-                {
-                    // multiply would overflow
-                    out_length = (int32_t )ascii85_err_decode_overflow; // bad input
-                    break; // leave while loop early to report error
-                }
-                else
-                {
-                    uint8_t addend = inp[in_rover++] - base_char;
-
-                    chunk *= 85u; // multiply will not overflow due to test above
-
-                    if (chunk > (UINT32_MAX - addend))
-                    {
-                        /// add would overflow
-                        out_length = (int32_t )ascii85_err_decode_overflow; // bad input
-                        break; // leave while loop early to report error
-                    }
-                    else
-                    {
-                        chunk += addend;
-                    }
-                }
-            }
-            else
-            {
-                chunk  = inp[in_rover++] - base_char;
-                chunk *= 85u; // max: 84 * 85 = 7,140
-                chunk += ((in_rover < in_length) ? (inp[in_rover++] - base_char) : 84u);
-                chunk *= 85u; // max: (84 * 85 + 84) * 85 = 614,040
-                chunk += ((in_rover < in_length) ? (inp[in_rover++] - base_char) : 84u);
-                chunk *= 85u; // max: (((84 * 85 + 84) * 85) + 84) * 85 = 52,200,540
-                chunk += ((in_rover < in_length) ? (inp[in_rover++] - base_char) : 84u);
-                // max: (((((84 * 85 + 84) * 85) + 84) * 85) + 84) * 85 = 4,437,053,040 oops! 0x108780E70
-                if (chunk > (UINT32_MAX / 85u))
-                {
-                    // multiply would overflow
-                    out_length = (int32_t )ascii85_err_decode_overflow; // bad input
-                    break; // leave while loop early to report error
-                }
-                else
-                {
-                    uint8_t addend = (uint8_t )((in_rover < in_length) ? (inp[in_rover++] - base_char) : 84u);
-
-                    chunk *= 85u; // multiply will not overflow due to test above
-
-                    if (chunk > (UINT32_MAX - addend))
-                    {
-                        /// add would overflow
-                        out_length = (int32_t )ascii85_err_decode_overflow; // bad input
-                        break; // leave while loop early to report error
-                    }
-                    else
-                    {
-                        chunk += addend;
-                    }
-                }
-            }
-
-            outp[out_length + 3] = (chunk % 256u);
-            chunk /= 256u;
-            outp[out_length + 2] = (chunk % 256u);
-            chunk /= 256u;
-            outp[out_length + 1] = (chunk % 256u);
-            chunk /= 256u;
-            outp[out_length    ] = (uint8_t )chunk;
-            // we don't need (chunk % 256u) on the last line since ((((2^32 - 1) / 256u) / 256u) / 256u) = 255
-
-            if (chunk_len >= 5)
-            {
-                out_length += 4;
-            }
-            else
-            {
-                out_length += (chunk_len - 1); // see note above re: Ascii85 length
-            }
-        }
-    }
-
-    return out_length;
-}
-
-int main(int argc, char **argv) {
-    char out_enc[BUFSIZ];
-    uint8_t out_dec[BUFSIZ];
-    size_t buflen;
-    int32_t siz_enc, siz_dec;
-
-#if ENDECODE_NUL_AS_Z
-    printf("Encoding NUL characters won't work from cmdline!\n");
-#endif
-    if (argc != 2) {
-        printf("usage: %s [BINARY-DATA]\n", (argc > 0 ? argv[0] : "null"));
-        exit(1);
-    }
-
-    memset(out_enc, 0, sizeof out_enc);
-    memset(out_dec, 0, sizeof out_dec);
-
-    buflen = strlen(argv[1]);
-    siz_enc = encode_ascii85((uint8_t *) argv[1], buflen, out_enc, sizeof out_enc - 1);
-    printf("Encoded: \"%.*s\"\n", siz_enc, (char *) out_enc);
-    siz_dec = decode_ascii85(out_enc, siz_enc, out_dec, sizeof out_dec - 1);
-    printf("Decoded: \"%.*s\"\n", siz_dec, (char *) out_dec);
-
-    if ((int32_t) buflen == siz_dec &&
-        memcmp(out_dec, argv[1], buflen) == 0)
-    {
-        printf("%s: Ok!\n", argv[0]);
-    } else printf("%s: FAIL!\n", argv[0]);
-
-    return 0;
-}