usr: Add glitch-art 'screensave' program

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 116 insertions, 0 deletions

diff --git a/usr.bin/screensave/screensave.c b/usr.bin/screensave/screensave.c
new file mode 100644
index 0000000..172ab8b
--- /dev/null
+++ b/usr.bin/screensave/screensave.c
@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <stdio.h>
+#include <time.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <libgfx/draw.h>
+#include <libgfx/gfx.h>
+
+static struct gfx_ctx ctx;
+
+static ssize_t
+rand_bytes(char *buf, size_t len)
+{
+    ssize_t retval;
+    int fd;
+
+    fd = open("/dev/random", O_RDONLY);
+    if (fd < 0) {
+        return fd;
+    }
+
+    if ((retval = read(fd, buf, len)) < 0) {
+        close(fd);
+        return retval;
+    }
+
+    close(fd);
+    return retval;
+}
+
+static void
+screensave(void)
+{
+    size_t n_iter = 0;          /* Monotonic */
+    struct timespec ts;
+    char randbuf[2];
+    color_t curpix, nextpix;
+    uint8_t step = 0;
+
+    ts.tv_sec = 0;
+    ts.tv_nsec = 70000000;
+
+    /* Begin the radiation ::) */
+    for (;;) {
+        rand_bytes(randbuf, sizeof(randbuf));
+        for (size_t i = 0; i < (ctx.fb_size / 4) - 1; i += step + 1) {
+            curpix = ctx.io[i];
+            nextpix = ctx.io[i + 1];
+
+            /* If a multiple of 15, AND, otherwise XOR */
+            if ((n_iter & 15) != 0) {
+                curpix ^= randbuf[0] & 3;
+                nextpix ^= (curpix | (nextpix << 1));
+                nextpix ^= step;
+            } else {
+                curpix &= randbuf[0] & 3;
+                nextpix &= (curpix | (nextpix << 1));
+                nextpix &= step;
+            }
+
+            ctx.io[i] = curpix;
+            ctx.io[i + 1] = nextpix;
+        }
+
+        sleep(&ts, &ts);
+        if ((++step) > 50) {
+            step = 0;
+        }
+        ++n_iter;
+    }
+}
+
+int
+main(void)
+{
+    int error;
+
+    error = gfx_init(&ctx);
+    if (error < 0) {
+        printf("could not init libgfx\n");
+        return error;
+    }
+
+    screensave();
+    gfx_cleanup(&ctx);
+    return 0;
+}