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286 lines
10 KiB
C
286 lines
10 KiB
C
/*
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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* All rights reserved.
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*
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* This source code is licensed under both the BSD-style license (found in the
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* LICENSE file in the root directory of this source tree) and the GPLv2 (found
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* in the COPYING file in the root directory of this source tree).
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* You may select, at your option, one of the above-listed licenses.
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*/
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/* Implementation notes:
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*
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* This is a very simple lorem ipsum generator
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* which features a static list of words
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* and print them one after another randomly
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* with a fake sentence / paragraph structure.
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*
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* The goal is to generate a printable text
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* that can be used to fake a text compression scenario.
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* The resulting compression / ratio curve of the lorem ipsum generator
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* is more satisfying than the previous statistical generator,
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* which was initially designed for entropy compression,
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* and lacks a regularity more representative of text.
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*
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* The compression ratio achievable on the generated lorem ipsum
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* is still a bit too good, presumably because the dictionary is too small.
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* It would be possible to create some more complex scheme,
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* notably by enlarging the dictionary with a word generator,
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* and adding grammatical rules (composition) and syntax rules.
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* But that's probably overkill for the intended goal.
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*/
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#include "lorem.h"
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#include <assert.h>
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#include <limits.h> /* INT_MAX */
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#include <string.h> /* memcpy */
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#define WORD_MAX_SIZE 20
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/* Define the word pool */
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static const char* kWords[] = {
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"lorem", "ipsum", "dolor", "sit", "amet",
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"consectetur", "adipiscing", "elit", "sed", "do",
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"eiusmod", "tempor", "incididunt", "ut", "labore",
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"et", "dolore", "magna", "aliqua", "dis",
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"lectus", "vestibulum", "mattis", "ullamcorper", "velit",
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"commodo", "a", "lacus", "arcu", "magnis",
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"parturient", "montes", "nascetur", "ridiculus", "mus",
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"mauris", "nulla", "malesuada", "pellentesque", "eget",
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"gravida", "in", "dictum", "non", "erat",
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"nam", "voluptat", "maecenas", "blandit", "aliquam",
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"etiam", "enim", "lobortis", "scelerisque", "fermentum",
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"dui", "faucibus", "ornare", "at", "elementum",
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"eu", "facilisis", "odio", "morbi", "quis",
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"eros", "donec", "ac", "orci", "purus",
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"turpis", "cursus", "leo", "vel", "porta",
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"consequat", "interdum", "varius", "vulputate", "aliquet",
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"pharetra", "nunc", "auctor", "urna", "id",
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"metus", "viverra", "nibh", "cras", "mi",
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"unde", "omnis", "iste", "natus", "error",
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"perspiciatis", "voluptatem", "accusantium", "doloremque", "laudantium",
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"totam", "rem", "aperiam", "eaque", "ipsa",
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"quae", "ab", "illo", "inventore", "veritatis",
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"quasi", "architecto", "beatae", "vitae", "dicta",
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"sunt", "explicabo", "nemo", "ipsam", "quia",
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"voluptas", "aspernatur", "aut", "odit", "fugit",
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"consequuntur", "magni", "dolores", "eos", "qui",
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"ratione", "sequi", "nesciunt", "neque", "porro",
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"quisquam", "est", "dolorem", "adipisci", "numquam",
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"eius", "modi", "tempora", "incidunt", "magnam",
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"quaerat", "ad", "minima", "veniam", "nostrum",
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"ullam", "corporis", "suscipit", "laboriosam", "nisi",
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"aliquid", "ex", "ea", "commodi", "consequatur",
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"autem", "eum", "iure", "voluptate", "esse",
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"quam", "nihil", "molestiae", "illum", "fugiat",
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"quo", "pariatur", "vero", "accusamus", "iusto",
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"dignissimos", "ducimus", "blanditiis", "praesentium", "voluptatum",
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"deleniti", "atque", "corrupti", "quos", "quas",
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"molestias", "excepturi", "sint", "occaecati", "cupiditate",
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"provident", "similique", "culpa", "officia", "deserunt",
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"mollitia", "animi", "laborum", "dolorum", "fuga",
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"harum", "quidem", "rerum", "facilis", "expedita",
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"distinctio", "libero", "tempore", "cum", "soluta",
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"nobis", "eligendi", "optio", "cumque", "impedit",
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"minus", "quod", "maxime", "placeat", "facere",
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"possimus", "assumenda", "repellendus", "temporibus", "quibusdam",
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"officiis", "debitis", "saepe", "eveniet", "voluptates",
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"repudiandae", "recusandae", "itaque", "earum", "hic",
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"tenetur", "sapiente", "delectus", "reiciendis", "cillum",
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"maiores", "alias", "perferendis", "doloribus", "asperiores",
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"repellat", "minim", "nostrud", "exercitation", "ullamco",
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"laboris", "aliquip", "duis", "aute", "irure",
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};
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static const unsigned kNbWords = sizeof(kWords) / sizeof(kWords[0]);
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/* simple 1-dimension distribution, based on word's length, favors small words
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*/
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static const int kWeights[] = { 0, 8, 6, 4, 3, 2 };
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static const unsigned kNbWeights = sizeof(kWeights) / sizeof(kWeights[0]);
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#define DISTRIB_SIZE_MAX 650
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static int g_distrib[DISTRIB_SIZE_MAX] = { 0 };
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static unsigned g_distribCount = 0;
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static void countFreqs(
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const char* words[],
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size_t nbWords,
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const int* weights,
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unsigned long nbWeights)
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{
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unsigned total = 0;
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size_t w;
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for (w = 0; w < nbWords; w++) {
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unsigned long len = strlen(words[w]);
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int lmax;
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if (len >= nbWeights)
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len = nbWeights - 1;
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lmax = weights[len];
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total += (unsigned)lmax;
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}
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g_distribCount = total;
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assert(g_distribCount <= DISTRIB_SIZE_MAX);
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}
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static void init_word_distrib(
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const char* words[],
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size_t nbWords,
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const int* weights,
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unsigned long nbWeights)
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{
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size_t w, d = 0;
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countFreqs(words, nbWords, weights, nbWeights);
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for (w = 0; w < nbWords; w++) {
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unsigned long len = strlen(words[w]);
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int l, lmax;
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if (len >= nbWeights)
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len = nbWeights - 1;
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lmax = weights[len];
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for (l = 0; l < lmax; l++) {
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g_distrib[d++] = (int)w;
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}
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}
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}
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/* Note: this unit only works when invoked sequentially.
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* No concurrent access is allowed */
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static char* g_ptr = NULL;
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static size_t g_nbChars = 0;
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static size_t g_maxChars = 10000000;
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static unsigned g_randRoot = 0;
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#define RDG_rotl32(x, r) ((x << r) | (x >> (32 - r)))
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static unsigned LOREM_rand(unsigned range)
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{
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static const unsigned prime1 = 2654435761U;
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static const unsigned prime2 = 2246822519U;
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unsigned rand32 = g_randRoot;
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rand32 *= prime1;
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rand32 ^= prime2;
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rand32 = RDG_rotl32(rand32, 13);
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g_randRoot = rand32;
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return (unsigned)(((unsigned long long)rand32 * range) >> 32);
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}
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static void writeLastCharacters(void)
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{
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size_t lastChars = g_maxChars - g_nbChars;
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assert(g_maxChars >= g_nbChars);
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if (lastChars == 0)
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return;
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g_ptr[g_nbChars++] = '.';
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if (lastChars > 2) {
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memset(g_ptr + g_nbChars, ' ', lastChars - 2);
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}
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if (lastChars > 1) {
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g_ptr[g_maxChars - 1] = '\n';
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}
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g_nbChars = g_maxChars;
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}
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static void generateWord(const char* word, const char* separator, int upCase)
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{
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size_t const len = strlen(word) + strlen(separator);
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if (g_nbChars + len > g_maxChars) {
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writeLastCharacters();
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return;
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}
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memcpy(g_ptr + g_nbChars, word, strlen(word));
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if (upCase) {
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static const char toUp = 'A' - 'a';
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g_ptr[g_nbChars] = (char)(g_ptr[g_nbChars] + toUp);
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}
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g_nbChars += strlen(word);
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memcpy(g_ptr + g_nbChars, separator, strlen(separator));
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g_nbChars += strlen(separator);
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}
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static int about(unsigned target)
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{
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return (int)(LOREM_rand(target) + LOREM_rand(target) + 1);
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}
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/* Function to generate a random sentence */
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static void generateSentence(int nbWords)
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{
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int commaPos = about(9);
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int comma2 = commaPos + about(7);
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int qmark = (LOREM_rand(11) == 7);
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const char* endSep = qmark ? "? " : ". ";
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int i;
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for (i = 0; i < nbWords; i++) {
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int const wordID = g_distrib[LOREM_rand(g_distribCount)];
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const char* const word = kWords[wordID];
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const char* sep = " ";
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if (i == commaPos)
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sep = ", ";
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if (i == comma2)
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sep = ", ";
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if (i == nbWords - 1)
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sep = endSep;
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generateWord(word, sep, i == 0);
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}
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}
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static void generateParagraph(int nbSentences)
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{
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int i;
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for (i = 0; i < nbSentences; i++) {
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int wordsPerSentence = about(11);
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generateSentence(wordsPerSentence);
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}
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if (g_nbChars < g_maxChars) {
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g_ptr[g_nbChars++] = '\n';
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}
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if (g_nbChars < g_maxChars) {
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g_ptr[g_nbChars++] = '\n';
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}
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}
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/* It's "common" for lorem ipsum generators to start with the same first
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* pre-defined sentence */
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static void generateFirstSentence(void)
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{
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int i;
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for (i = 0; i < 18; i++) {
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const char* word = kWords[i];
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const char* separator = " ";
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if (i == 4)
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separator = ", ";
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if (i == 7)
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separator = ", ";
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generateWord(word, separator, i == 0);
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}
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generateWord(kWords[18], ". ", 0);
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}
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size_t
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LOREM_genBlock(void* buffer, size_t size, unsigned seed, int first, int fill)
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{
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g_ptr = (char*)buffer;
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assert(size < INT_MAX);
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g_maxChars = size;
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g_nbChars = 0;
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g_randRoot = seed;
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if (g_distribCount == 0) {
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init_word_distrib(kWords, kNbWords, kWeights, kNbWeights);
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}
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if (first) {
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generateFirstSentence();
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}
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while (g_nbChars < g_maxChars) {
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int sentencePerParagraph = about(7);
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generateParagraph(sentencePerParagraph);
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if (!fill)
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break; /* only generate one paragraph in not-fill mode */
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}
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g_ptr = NULL;
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return g_nbChars;
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}
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void LOREM_genBuffer(void* buffer, size_t size, unsigned seed)
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{
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LOREM_genBlock(buffer, size, seed, 1, 1);
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}
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