ansi: show ANSI art in a UTF-8 terminal, or as plain or shaded text
Draws an .ans file into a grid the way an ANSI-BBS terminal would (cursor moves, the wrap at the SAUCE width, iCE colours) and writes it out as UTF-8: in colour, --plain, or --mono with coloured areas shaded by brightness. info prints the SAUCE record. One C99 file with no dependencies.
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@@ -0,0 +1,473 @@
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/*
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* ansi - show ANSI art in a modern terminal, or turn it into plain text.
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*
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* An .ans file is CP437 text with ANSI escape codes, usually laid out for an
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* 80-column terminal that wraps it. ansi draws it into a grid the way a BBS
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* terminal would (cursor moves, wrapping, iCE colours, the SAUCE record), then
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* writes the grid out as UTF-8: in colour, as plain characters, or in
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* monochrome with coloured areas redrawn as shading.
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*/
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#define _POSIX_C_SOURCE 200809L
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#define VERSION "1.0.0"
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#define MAX_WIDTH 1000
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#define MAX_CELLS (1u << 24) /* about 80 MB of grid; art past it is dropped */
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/* CP437 as UTF-8. 0x01-0x1F are the glyphs art uses them for, not controls. */
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static const char *const cp437[256] = {
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" ", "☺", "☻", "♥", "♦", "♣", "♠", "•",
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"◘", "○", "◙", "♂", "♀", "♪", "♫", "☼",
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"►", "◄", "↕", "‼", "¶", "§", "▬", "↨",
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"↑", "↓", "→", "←", "∟", "↔", "▲", "▼",
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" ", "!", "\"", "#", "$", "%", "&", "'",
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"(", ")", "*", "+", ",", "-", ".", "/",
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"0", "1", "2", "3", "4", "5", "6", "7",
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"8", "9", ":", ";", "<", "=", ">", "\?",
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"@", "A", "B", "C", "D", "E", "F", "G",
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"H", "I", "J", "K", "L", "M", "N", "O",
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"P", "Q", "R", "S", "T", "U", "V", "W",
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"X", "Y", "Z", "[", "\\", "]", "^", "_",
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"`", "a", "b", "c", "d", "e", "f", "g",
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"h", "i", "j", "k", "l", "m", "n", "o",
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"p", "q", "r", "s", "t", "u", "v", "w",
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"x", "y", "z", "{", "|", "}", "~", "⌂",
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"Ç", "ü", "é", "â", "ä", "à", "å", "ç",
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"ê", "ë", "è", "ï", "î", "ì", "Ä", "Å",
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"É", "æ", "Æ", "ô", "ö", "ò", "û", "ù",
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"ÿ", "Ö", "Ü", "¢", "£", "¥", "₧", "ƒ",
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"á", "í", "ó", "ú", "ñ", "Ñ", "ª", "º",
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"¿", "⌐", "¬", "½", "¼", "¡", "«", "»",
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"░", "▒", "▓", "│", "┤", "╡", "╢", "╖",
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"╕", "╣", "║", "╗", "╝", "╜", "╛", "┐",
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"└", "┴", "┬", "├", "─", "┼", "╞", "╟",
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"╚", "╔", "╩", "╦", "╠", "═", "╬", "╧",
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"╨", "╤", "╥", "╙", "╘", "╒", "╓", "╫",
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"╪", "┘", "┌", "█", "▄", "▌", "▐", "▀",
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"α", "ß", "Γ", "π", "Σ", "σ", "µ", "τ",
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"Φ", "Θ", "Ω", "δ", "∞", "φ", "ε", "∩",
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"≡", "±", "≥", "≤", "⌠", "⌡", "÷", "≈",
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"°", "∙", "·", "√", "ⁿ", "²", "■", " ",
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};
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/* How bright each of the 16 CGA colours looks (CIE L*, 0-100). */
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static const double lightness[16] = {
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0.0000, 35.0952, 60.5599, 45.6931, 19.6482, 40.3255, 63.0540, 69.6102,
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36.1459, 60.2599, 88.9731, 97.4042, 46.5096, 65.7308, 91.9852, 100.0000
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};
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enum mode { COLOUR, PLAIN, MONO };
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typedef struct {
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unsigned char ch; /* CP437 byte; 0 is stored as a space */
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unsigned char fg, bg; /* 0-7 */
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unsigned char bold, blink; /* blink is iCE: the bright background */
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} cell;
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typedef struct {
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char title[36], author[21], group[21], date[9];
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unsigned width, height, comments, flags;
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unsigned char datatype, filetype;
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int present;
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} sauce;
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typedef struct {
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cell *cells;
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size_t rows, cap;
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unsigned width;
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} grid;
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static const char *progname = "ansi";
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static void *xrealloc(void *p, size_t n)
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{
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p = realloc(p, n);
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if (!p) {
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fprintf(stderr, "%s: out of memory\n", progname);
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exit(2);
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}
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return p;
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}
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static unsigned char *slurp(const char *path, size_t *len)
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{
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FILE *f = strcmp(path, "-") ? fopen(path, "rb") : stdin;
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if (!f) {
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fprintf(stderr, "%s: %s: %s\n", progname, path, strerror(errno));
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return NULL;
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}
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size_t cap = 65536, n = 0;
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unsigned char *buf = xrealloc(NULL, cap);
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for (;;) {
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size_t got = fread(buf + n, 1, cap - n, f);
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n += got;
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if (n < cap)
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break;
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buf = xrealloc(buf, cap *= 2);
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}
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if (ferror(f)) {
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fprintf(stderr, "%s: %s: read error\n", progname, path);
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free(buf);
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buf = NULL;
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}
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if (f != stdin)
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fclose(f);
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*len = n;
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return buf;
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}
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static void field(char *dst, const unsigned char *src, size_t n)
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{
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memcpy(dst, src, n);
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dst[n] = '\0';
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for (size_t i = n; i > 0 && (dst[i - 1] == ' ' || dst[i - 1] == '\0'); i--)
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dst[i - 1] = '\0';
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}
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static unsigned u16(const unsigned char *p) { return p[0] | p[1] << 8; }
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/* Read the SAUCE record and shorten len to the art itself. */
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static void read_sauce(const unsigned char *data, size_t *len, sauce *s)
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{
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memset(s, 0, sizeof *s);
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s->width = 80;
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if (*len >= 128 && !memcmp(data + *len - 128, "SAUCE00", 7)) {
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const unsigned char *r = data + *len - 128;
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s->present = 1;
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field(s->title, r + 7, 35);
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field(s->author, r + 42, 20);
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field(s->group, r + 62, 20);
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field(s->date, r + 82, 8);
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s->datatype = r[94];
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s->filetype = r[95];
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s->comments = r[104];
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s->flags = r[105];
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s->height = u16(r + 98);
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if (s->datatype == 1 && s->filetype <= 1 && u16(r + 96) && u16(r + 96) <= MAX_WIDTH)
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s->width = u16(r + 96);
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size_t trailer = 128 + (s->comments ? 5 + 64 * s->comments : 0);
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*len = *len > trailer ? *len - trailer : 0;
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}
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const unsigned char *eof = memchr(data, 0x1A, *len);
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if (eof)
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*len = eof - data;
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}
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/* The cell at x, y, growing the grid to reach it; NULL past MAX_CELLS. */
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static cell *at(grid *g, unsigned x, size_t y)
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{
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if (y >= MAX_CELLS / g->width)
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return NULL;
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if (y >= g->rows) {
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size_t want = y + 1;
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if (want > g->cap) {
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g->cap = want * 2;
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g->cells = xrealloc(g->cells, g->cap * g->width * sizeof(cell));
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}
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for (size_t r = g->rows; r < want; r++)
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for (unsigned c = 0; c < g->width; c++)
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g->cells[r * g->width + c] = (cell){' ', 7, 0, 0, 0};
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g->rows = want;
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}
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return &g->cells[y * g->width + x];
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}
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/* Lay the art out in a grid, the way an ANSI-BBS terminal of the given width would. */
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static void render(grid *g, const unsigned char *d, size_t n)
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{
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unsigned x = 0, sx = 0, w = g->width;
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size_t y = 0, sy = 0;
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unsigned char fg = 7, bg = 0, bold = 0, blink = 0;
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for (size_t i = 0; i < n;) {
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unsigned char b = d[i];
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if (b == 0x1B && i + 1 < n && d[i + 1] == '[') {
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size_t j = i + 2, ps = j;
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while (j < n && d[j] >= 0x30 && d[j] <= 0x3F)
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j++;
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size_t pe = j;
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while (j < n && d[j] >= 0x20 && d[j] <= 0x2F)
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j++;
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if (j >= n || d[j] < 0x40 || d[j] > 0x7E)
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break; /* a broken sequence ends the art */
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unsigned char cmd = d[j];
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i = j + 1;
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if (pe > ps && d[ps] == '?')
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continue; /* private modes, such as line wrap */
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unsigned p[16], np = 0;
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if (pe > ps) {
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p[0] = 0;
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np = 1;
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for (size_t k = ps; k < pe; k++) {
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if (d[k] == ';') {
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if (np < 16)
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p[np++] = 0;
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} else if (d[k] >= '0' && d[k] <= '9' && np <= 16) {
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p[np - 1] = p[np - 1] * 10 + (d[k] - '0');
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}
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}
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}
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unsigned arg = np && p[0] ? p[0] : 1;
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switch (cmd) {
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case 'm':
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if (!np)
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p[np++] = 0;
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for (unsigned k = 0; k < np; k++) {
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unsigned v = p[k];
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if (v == 0)
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fg = 7, bg = 0, bold = 0, blink = 0;
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else if (v == 1)
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bold = 1;
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else if (v == 5)
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blink = 1;
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else if (v == 22)
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bold = 0;
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else if (v == 25)
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blink = 0;
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else if (v >= 30 && v <= 37)
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fg = v - 30;
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else if (v == 39)
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fg = 7;
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else if (v >= 40 && v <= 47)
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bg = v - 40;
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else if (v == 49)
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bg = 0;
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}
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break;
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case 'C': x = x + arg < w ? x + arg : w; break;
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case 'D': x = x > arg ? x - arg : 0; break;
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case 'A': y = y > arg ? y - arg : 0; break;
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case 'B': y += arg; break;
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case 'H':
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case 'f':
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y = (np && p[0] ? p[0] : 1) - 1;
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x = (np > 1 && p[1] ? p[1] : 1) - 1;
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if (x > w - 1)
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x = w - 1;
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break;
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case 's': sx = x, sy = y; break;
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case 'u': x = sx, y = sy; break;
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case 'J':
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if (arg == 2)
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g->rows = 0, x = 0, y = 0;
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break;
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}
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continue;
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}
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i++;
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if (b == '\r') {
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x = 0;
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} else if (b == '\n') {
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x = 0, y++;
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} else if (b == 0x1B) {
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/* a lone escape */
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} else {
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unsigned count = b == '\t' ? 8 - x % 8 : 1;
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unsigned char ch = b == '\t' || b == 0 ? ' ' : b;
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while (count--) {
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if (x >= w)
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x = 0, y++; /* wrap only when the next character arrives */
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cell *c = at(g, x, y);
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if (c)
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*c = (cell){ch, fg, bg, bold, blink};
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x++;
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}
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}
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}
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}
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static int same(const cell *a, const cell *b)
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{
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return a->fg == b->fg && a->bg == b->bg && a->bold == b->bold && a->blink == b->blink;
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}
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static int level(double l)
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{
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return l < 15 ? 0 : l < 40 ? 1 : l < 60 ? 2 : l < 85 ? 3 : 4;
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}
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/* How much of a cell the foreground covers, top half and bottom half; -1 if not a block. */
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static double cover(unsigned char ch, int half)
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{
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switch (ch) {
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case ' ': return 0;
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case 0xDB: return 1; /* full block */
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case 0xDF: return half ? 0 : 1; /* upper half */
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case 0xDC: return half ? 1 : 0; /* lower half */
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case 0xDD: case 0xDE: return .5; /* left and right halves */
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case 0xB0: return .25;
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case 0xB1: return .5;
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case 0xB2: return .75;
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default: return -1;
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}
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}
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/* One character standing in for a coloured cell: shading by brightness, half blocks for halves. */
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static const char *mono(const cell *c)
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{
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static const char *const shade[5] = {" ", "░", "▒", "▓", "█"};
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if (cover(c->ch, 0) < 0)
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return cp437[c->ch];
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double f = lightness[c->fg + 8 * c->bold], b = lightness[c->bg + 8 * c->blink];
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int top = level(cover(c->ch, 0) * f + (1 - cover(c->ch, 0)) * b);
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int bot = level(cover(c->ch, 1) * f + (1 - cover(c->ch, 1)) * b);
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if (top - bot >= 2)
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return "▀";
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if (bot - top >= 2)
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return "▄";
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return shade[top > bot ? top : bot];
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}
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static void emit(const grid *g, enum mode m, FILE *out)
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{
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/* Lines are built first so that trailing blank ones can be dropped. */
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char **lines = xrealloc(NULL, (g->rows + 1) * sizeof *lines);
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size_t nlines = 0;
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for (size_t y = 0; y < g->rows; y++) {
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const cell *row = &g->cells[y * g->width];
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unsigned len = g->width;
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while (len && row[len - 1].ch == ' ' && !row[len - 1].bg && !row[len - 1].blink)
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len--;
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size_t cap = 64 + len * 24, n = 0;
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char *s = xrealloc(NULL, cap);
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const cell *last = NULL;
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for (unsigned x = 0; x < len; x++) {
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const cell *c = &row[x];
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const char *glyph = m == MONO ? mono(c) : cp437[c->ch];
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if (m == COLOUR) {
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int keep = last && (same(c, last) ||
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(c->ch == ' ' && c->bg == last->bg && c->blink == last->blink));
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if (!keep) {
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n += sprintf(s + n, "\033[0;%s%d;%dm", c->bold ? "1;" : "",
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30 + c->fg, (c->blink ? 100 : 40) + c->bg);
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last = c;
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}
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}
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size_t gl = strlen(glyph);
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memcpy(s + n, glyph, gl);
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n += gl;
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}
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if (m == COLOUR && len)
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n += sprintf(s + n, "\033[0m");
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else
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while (n && s[n - 1] == ' ')
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n--;
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s[n] = '\0';
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lines[nlines++] = s;
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}
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while (nlines && !*lines[nlines - 1])
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free(lines[--nlines]);
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for (size_t i = 0; i < nlines; i++) {
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fputs(lines[i], out);
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fputc('\n', out);
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free(lines[i]);
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}
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free(lines);
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}
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static void info(const char *path, const sauce *s, const grid *g, FILE *out)
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{
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static const char *const types[] = {"ASCII", "ANSi", "ANSiMation"};
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fprintf(out, "%s\n", path);
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if (!s->present) {
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fprintf(out, " no SAUCE record; laid out at %u columns, %zu row%s\n", g->width, g->rows,
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g->rows == 1 ? "" : "s");
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return;
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}
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if (*s->title) fprintf(out, " title %s\n", s->title);
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if (*s->author) fprintf(out, " author %s\n", s->author);
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if (*s->group) fprintf(out, " group %s\n", s->group);
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if (strlen(s->date) == 8)
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fprintf(out, " date %.4s-%.2s-%.2s\n", s->date, s->date + 4, s->date + 6);
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fprintf(out, " size %ux%u", s->width, s->height ? s->height : (unsigned)g->rows);
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if (s->datatype == 1 && s->filetype <= 2)
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fprintf(out, ", %s", types[s->filetype]);
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if (s->flags & 1)
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fprintf(out, ", iCE colours");
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fputc('\n', out);
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}
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static void usage(FILE *out)
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{
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fprintf(out,
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"usage: %s [-p | -m] [-w WIDTH] [FILE...]\n"
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" %s info FILE...\n"
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"\n"
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"Show ANSI art (CP437 with ANSI colour codes, as .ans files are) in a UTF-8\n"
|
||||
"terminal, laid out the way a BBS terminal would draw it. With no FILE, or\n"
|
||||
"when FILE is -, it reads standard input.\n"
|
||||
"\n"
|
||||
" -p, --plain the characters only, no colour\n"
|
||||
" -m, --mono no colour, with coloured areas redrawn as shading by\n"
|
||||
" brightness (for newsgroups and mail that show no colour)\n"
|
||||
" -w, --width N lay the art out N columns wide (default: SAUCE, else 80)\n"
|
||||
" info print each file's SAUCE record: title, artist, size\n"
|
||||
" -h, --help show this help\n"
|
||||
" -V, --version show the version\n"
|
||||
"\n"
|
||||
"Examples:\n"
|
||||
" %s piece.ans | less -R\n"
|
||||
" %s --mono piece.ans > piece.txt\n",
|
||||
progname, progname, progname, progname);
|
||||
}
|
||||
|
||||
int main(int argc, char **argv)
|
||||
{
|
||||
enum mode m = COLOUR;
|
||||
unsigned width = 0;
|
||||
int show_info = 0, status = 0, files = 0;
|
||||
|
||||
for (int i = 1; i < argc; i++) {
|
||||
const char *a = argv[i];
|
||||
if (!strcmp(a, "-h") || !strcmp(a, "--help") || !strcmp(a, "help")) {
|
||||
usage(stdout);
|
||||
return 0;
|
||||
} else if (!strcmp(a, "-V") || !strcmp(a, "--version")) {
|
||||
printf("%s %s\n", progname, VERSION);
|
||||
return 0;
|
||||
} else if (!strcmp(a, "-p") || !strcmp(a, "--plain")) {
|
||||
m = PLAIN;
|
||||
} else if (!strcmp(a, "-m") || !strcmp(a, "--mono")) {
|
||||
m = MONO;
|
||||
} else if (!strcmp(a, "-w") || !strcmp(a, "--width")) {
|
||||
if (++i >= argc || (width = (unsigned)strtoul(argv[i], NULL, 10)) < 1 || width > 1000) {
|
||||
fprintf(stderr, "%s: --width needs a number from 1 to 1000\n", progname);
|
||||
return 1;
|
||||
}
|
||||
} else if (!strcmp(a, "info") && files == 0 && !show_info) {
|
||||
show_info = 1;
|
||||
} else if (a[0] == '-' && a[1]) {
|
||||
fprintf(stderr, "%s: unknown option %s\n", progname, a);
|
||||
usage(stderr);
|
||||
return 1;
|
||||
} else {
|
||||
argv[++files] = argv[i]; /* keep the file names at the front */
|
||||
}
|
||||
}
|
||||
if (!files)
|
||||
argv[++files] = "-";
|
||||
|
||||
for (int f = 1; f <= files; f++) {
|
||||
size_t len;
|
||||
unsigned char *data = slurp(argv[f], &len);
|
||||
if (!data) {
|
||||
status = 2;
|
||||
continue;
|
||||
}
|
||||
sauce s;
|
||||
read_sauce(data, &len, &s);
|
||||
grid g = {NULL, 0, 0, width ? width : s.width};
|
||||
render(&g, data, len);
|
||||
if (show_info)
|
||||
info(argv[f], &s, &g, stdout);
|
||||
else
|
||||
emit(&g, m, stdout);
|
||||
free(g.cells);
|
||||
free(data);
|
||||
}
|
||||
return status;
|
||||
}
|
||||
Reference in new issue
Block a user