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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>
void lolwut5Command(client *c);
void lolwut6Command(client *c);
void lolwut8Command(client *c);
/* The default target for LOLWUT if no matching version was found.
* This is what unstable versions of Redis will display. */
void lolwutUnstableCommand(client *c) {
sds rendered = sdsnew("Redis ver. ");
rendered = sdscat(rendered,REDIS_VERSION);
rendered = sdscatlen(rendered,"\n",1);
addReplyVerbatim(c,rendered,sdslen(rendered),"txt");
sdsfree(rendered);
}
/* LOLWUT [VERSION <version>] [... version specific arguments ...] */
void lolwutCommand(client *c) {
char *v = REDIS_VERSION;
char verstr[64];
if (c->argc >= 3 && !strcasecmp(c->argv[1]->ptr,"version")) {
long ver;
if (getLongFromObjectOrReply(c,c->argv[2],&ver,NULL) != C_OK) return;
snprintf(verstr,sizeof(verstr),"%u.0.0",(unsigned int)ver);
v = verstr;
/* Adjust argv/argc to filter the "VERSION ..." option, since the
* specific LOLWUT version implementations don't know about it
* and expect their arguments. */
c->argv += 2;
c->argc -= 2;
}
if ((v[0] == '5' && v[1] == '.' && v[2] != '9') ||
(v[0] == '4' && v[1] == '.' && v[2] == '9'))
lolwut5Command(c);
else if ((v[0] == '6' && v[1] == '.' && v[2] != '9') ||
(v[0] == '5' && v[1] == '.' && v[2] == '9'))
lolwut6Command(c);
else if ((v[0] == '8' && v[1] == '.' && v[2] != '9') ||
(v[0] == '7' && v[1] == '.' && v[2] == '9'))
lolwut8Command(c);
else
lolwutUnstableCommand(c);
/* Fix back argc/argv in case of VERSION argument. */
if (v == verstr) {
c->argv -= 2;
c->argc += 2;
}
}
/* ========================== LOLWUT Canvas ===============================
* Many LOLWUT versions will likely print some computer art to the screen.
* This is the case with LOLWUT 5 and LOLWUT 6, so here there is a generic
* canvas implementation that can be reused. */
/* Allocate and return a new canvas of the specified size. */
lwCanvas *lwCreateCanvas(int width, int height, int bgcolor) {
lwCanvas *canvas = zmalloc(sizeof(*canvas));
canvas->width = width;
canvas->height = height;
canvas->pixels = zmalloc((size_t)width*height);
memset(canvas->pixels,bgcolor,(size_t)width*height);
return canvas;
}
/* Free the canvas created by lwCreateCanvas(). */
void lwFreeCanvas(lwCanvas *canvas) {
zfree(canvas->pixels);
zfree(canvas);
}
/* Set a pixel to the specified color. Color is 0 or 1, where zero means no
* dot will be displayed, and 1 means dot will be displayed.
* Coordinates are arranged so that left-top corner is 0,0. You can write
* out of the size of the canvas without issues. */
void lwDrawPixel(lwCanvas *canvas, int x, int y, int color) {
if (x < 0 || x >= canvas->width ||
y < 0 || y >= canvas->height) return;
canvas->pixels[x+y*canvas->width] = color;
}
/* Return the value of the specified pixel on the canvas. */
int lwGetPixel(lwCanvas *canvas, int x, int y) {
if (x < 0 || x >= canvas->width ||
y < 0 || y >= canvas->height) return 0;
return canvas->pixels[x+y*canvas->width];
}
/* Draw a line from x1,y1 to x2,y2 using the Bresenham algorithm. */
void lwDrawLine(lwCanvas *canvas, int x1, int y1, int x2, int y2, int color) {
int dx = abs(x2-x1);
int dy = abs(y2-y1);
int sx = (x1 < x2) ? 1 : -1;
int sy = (y1 < y2) ? 1 : -1;
int err = dx-dy, e2;
while(1) {
lwDrawPixel(canvas,x1,y1,color);
if (x1 == x2 && y1 == y2) break;
e2 = err*2;
if (e2 > -dy) {
err -= dy;
x1 += sx;
}
if (e2 < dx) {
err += dx;
y1 += sy;
}
}
}
/* Draw a square centered at the specified x,y coordinates, with the specified
* rotation angle and size. In order to write a rotated square, we use the
* trivial fact that the parametric equation:
*
* x = sin(k)
* y = cos(k)
*
* Describes a circle for values going from 0 to 2*PI. So basically if we start
* at 45 degrees, that is k = PI/4, with the first point, and then we find
* the other three points incrementing K by PI/2 (90 degrees), we'll have the
* points of the square. In order to rotate the square, we just start with
* k = PI/4 + rotation_angle, and we are done.
*
* Of course the vanilla equations above will describe the square inside a
* circle of radius 1, so in order to draw larger squares we'll have to
* multiply the obtained coordinates, and then translate them. However this
* is much simpler than implementing the abstract concept of 2D shape and then
* performing the rotation/translation transformation, so for LOLWUT it's
* a good approach. */
void lwDrawSquare(lwCanvas *canvas, int x, int y, float size, float angle, int color) {
int px[4], py[4];
/* Adjust the desired size according to the fact that the square inscribed
* into a circle of radius 1 has the side of length SQRT(2). This way
* size becomes a simple multiplication factor we can use with our
* coordinates to magnify them. */
size /= 1.4142135623;
size = round(size);
/* Compute the four points. */
float k = M_PI/4 + angle;
for (int j = 0; j < 4; j++) {
px[j] = round(sin(k) * size + x);
py[j] = round(cos(k) * size + y);
k += M_PI/2;
}
/* Draw the square. */
for (int j = 0; j < 4; j++)
lwDrawLine(canvas,px[j],py[j],px[(j+1)%4],py[(j+1)%4],color);
}
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