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