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/*
* Copyright (c) 2018-Present, Redis Ltd.
* All rights reserved.
*
* Licensed under your choice of (a) the Redis Source Available License 2.0
* (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the
* GNU Affero General Public License v3 (AGPLv3).
*
* ----------------------------------------------------------------------------
*
* This file implements the LOLWUT command. The command should do something
* fun and interesting, and should be replaced by a new implementation at
* each new version of Redis.
*/
#include "server.h"
#include "lolwut.h"
#include <math.h>
/* Translate a group of 8 pixels (2x4 vertical rectangle) to the corresponding
* braille character. The byte should correspond to the pixels arranged as
* follows, where 0 is the least significant bit, and 7 the most significant
* bit:
*
* 0 3
* 1 4
* 2 5
* 6 7
*
* The corresponding utf8 encoded character is set into the three bytes
* pointed by 'output'.
*/
#include <stdio.h>
void lwTranslatePixelsGroup(int byte, char *output) {
int code = 0x2800 + byte;
/* Convert to unicode. This is in the U0800-UFFFF range, so we need to
* emit it like this in three bytes:
* 1110xxxx 10xxxxxx 10xxxxxx. */
output[0] = 0xE0 | (code >> 12); /* 1110-xxxx */
output[1] = 0x80 | ((code >> 6) & 0x3F); /* 10-xxxxxx */
output[2] = 0x80 | (code & 0x3F); /* 10-xxxxxx */
}
/* Schotter, the output of LOLWUT of Redis 5, is a computer graphic art piece
* generated by Georg Nees in the 60s. It explores the relationship between
* caos and order.
*
* The function creates the canvas itself, depending on the columns available
* in the output display and the number of squares per row and per column
* requested by the caller. */
lwCanvas *lwDrawSchotter(int console_cols, int squares_per_row, int squares_per_col) {
/* Calculate the canvas size. */
int canvas_width = console_cols*2;
int padding = canvas_width > 4 ? 2 : 0;
float square_side = (float)(canvas_width-padding*2) / squares_per_row;
int canvas_height = square_side * squares_per_col + padding*2;
lwCanvas *canvas = lwCreateCanvas(canvas_width, canvas_height, 0);
for (int y = 0; y < squares_per_col; y++) {
for (int x = 0; x < squares_per_row; x++) {
int sx = x * square_side + square_side/2 + padding;
int sy = y * square_side + square_side/2 + padding;
/* Rotate and translate randomly as we go down to lower
* rows. */
float angle = 0;
if (y > 1) {
float r1 = (float)rand() / (float) RAND_MAX / squares_per_col * y;
float r2 = (float)rand() / (float) RAND_MAX / squares_per_col * y;
float r3 = (float)rand() / (float) RAND_MAX / squares_per_col * y;
if (rand() % 2) r1 = -r1;
if (rand() % 2) r2 = -r2;
if (rand() % 2) r3 = -r3;
angle = r1;
sx += r2*square_side/3;
sy += r3*square_side/3;
}
lwDrawSquare(canvas,sx,sy,square_side,angle,1);
}
}
return canvas;
}
/* Converts the canvas to an SDS string representing the UTF8 characters to
* print to the terminal in order to obtain a graphical representation of the
* logical canvas. The actual returned string will require a terminal that is
* width/2 large and height/4 tall in order to hold the whole image without
* overflowing or scrolling, since each Barille character is 2x4. */
static sds renderCanvas(lwCanvas *canvas) {
sds text = sdsempty();
for (int y = 0; y < canvas->height; y += 4) {
for (int x = 0; x < canvas->width; x += 2) {
/* We need to emit groups of 8 bits according to a specific
* arrangement. See lwTranslatePixelsGroup() for more info. */
int byte = 0;
if (lwGetPixel(canvas,x,y)) byte |= (1<<0);
if (lwGetPixel(canvas,x,y+1)) byte |= (1<<1);
if (lwGetPixel(canvas,x,y+2)) byte |= (1<<2);
if (lwGetPixel(canvas,x+1,y)) byte |= (1<<3);
if (lwGetPixel(canvas,x+1,y+1)) byte |= (1<<4);
if (lwGetPixel(canvas,x+1,y+2)) byte |= (1<<5);
if (lwGetPixel(canvas,x,y+3)) byte |= (1<<6);
if (lwGetPixel(canvas,x+1,y+3)) byte |= (1<<7);
char unicode[3];
lwTranslatePixelsGroup(byte,unicode);
text = sdscatlen(text,unicode,3);
}
if (y != canvas->height-1) text = sdscatlen(text,"\n",1);
}
return text;
}
/* The LOLWUT command:
*
* LOLWUT [terminal columns] [squares-per-row] [squares-per-col]
*
* By default the command uses 66 columns, 8 squares per row, 12 squares
* per column.
*/
void lolwut5Command(client *c) {
long cols = 66;
long squares_per_row = 8;
long squares_per_col = 12;
/* Parse the optional arguments if any. */
if (c->argc > 1 &&
getLongFromObjectOrReply(c,c->argv[1],&cols,NULL) != C_OK)
return;
if (c->argc > 2 &&
getLongFromObjectOrReply(c,c->argv[2],&squares_per_row,NULL) != C_OK)
return;
if (c->argc > 3 &&
getLongFromObjectOrReply(c,c->argv[3],&squares_per_col,NULL) != C_OK)
return;
/* Limits. We want LOLWUT to be always reasonably fast and cheap to execute
* so we have maximum number of columns, rows, and output resolution. */
if (cols < 1) cols = 1;
if (cols > 1000) cols = 1000;
if (squares_per_row < 1) squares_per_row = 1;
if (squares_per_row > 200) squares_per_row = 200;
if (squares_per_col < 1) squares_per_col = 1;
if (squares_per_col > 200) squares_per_col = 200;
/* Generate some computer art and reply. */
lwCanvas *canvas = lwDrawSchotter(cols,squares_per_row,squares_per_col);
sds rendered = renderCanvas(canvas);
rendered = sdscat(rendered,
"\nGeorg Nees - schotter, plotter on paper, 1968. Redis ver. ");
rendered = sdscat(rendered,REDIS_VERSION);
rendered = sdscatlen(rendered,"\n",1);
addReplyVerbatim(c,rendered,sdslen(rendered),"txt");
sdsfree(rendered);
lwFreeCanvas(canvas);
}
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