X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/rigol/blobdiff_plain/a8982973a30709b358876498572df8d2e96ef5cf..3df147113765d5a8ba192795d2be9b7e3e295749:/png.c

diff --git a/png.c b/png.c
new file mode 100644
index 0000000..98d5993
--- /dev/null
+++ b/png.c
@@ -0,0 +1,117 @@
+#include <string.h>
+#include <stdint.h>
+#include <arpa/inet.h>
+#include <zlib.h>
+
+#include "png.h"
+
+/* Table of CRCs of all 8-bit messages. */
+static unsigned long crc_table[256];
+
+/* Flag: has the table been computed? Initially false. */
+static int crc_table_computed = 0;
+
+/* Make the table for a fast CRC. */
+static void make_crc_table(void)
+{
+	unsigned long c;
+	int n, k;
+
+	for (n = 0; n < 256; n++) {
+		c = (unsigned long) n;
+		for (k = 0; k < 8; k++) {
+			if (c & 1)
+				c = 0xedb88320L ^ (c >> 1);
+			else
+				c = c >> 1;
+		}
+		crc_table[n] = c;
+	}
+	crc_table_computed = 1;
+}
+
+/* Update a running CRC with the bytes buf[0..len-1]--the CRC
+   should be initialized to all 1's, and the transmitted value
+   is the 1's complement of the final running CRC (see the
+   crc() routine below). */
+
+static unsigned long update_crc(unsigned long crc, unsigned char *buf,
+		int len)
+{
+	unsigned long c = crc;
+	int n;
+
+	if (!crc_table_computed)
+		make_crc_table();
+	for (n = 0; n < len; n++) {
+		c = crc_table[(c ^ buf[n]) & 0xff] ^ (c >> 8);
+	}
+	return c;
+}
+
+/* Return the CRC of the bytes buf[0..len-1]. */
+static unsigned long crc(unsigned char *buf, int len)
+{
+	return update_crc(0xffffffffL, buf, len) ^ 0xffffffffL;
+}
+
+unsigned char *lcd2png(unsigned char *lcd, int *len)
+{
+	unsigned char screen_conv[320*234*3];
+	unsigned char lut[256][3];
+	unsigned char *image;
+	unsigned char *outpos;
+	static const unsigned char png[] = {137, 80, 78, 71, 13, 10, 26, 10};
+	static unsigned char ihdr[] = {'I', 'H', 'D', 'R',
+		0x00, 0x00, 0x01, 0x40, /* 320 - Width */
+		0x00, 0x00, 0x00, 0xea, /* 234 - Height */
+		0x08, /* Bit depth */
+		0x02, /* RGB Truecolor, Colour type */
+		0x00, /* Deflate, Compression method */
+		0x00, /* None, Filter method */
+		0x00  /* No interlace, Interlace method */
+		};
+	static unsigned char idat[] = {'I', 'D', 'A', 'T'};
+	static unsigned char iend[] = {'I', 'E', 'N', 'D'};
+	uint32_t l;
+	int i;
+	int toalloc = 0;
+
+	for(i = 0; i < 256; i++) {
+		lut[i][0] = ((i >> 6) * 0x55);
+		lut[i][1] = ((((i >> 3) & 7) * 0x49) >> 1);
+		lut[i][2] = (((i & 7) * 0x49) >> 1);
+	}
+
+	for(i = 0; i < sizeof(screen_conv); i += 3) {
+		screen_conv[i] = lut[lcd[i/3]][0];
+		screen_conv[i+1] = lut[lcd[i/3]][1];
+		screen_conv[i+2] = lut[lcd[i/3]][2];
+	}
+
+	image = malloc(320*234*2); /* TODO: FIXME! */
+	outpos = image;
+	memcpy(outpos, png, sizeof(png));
+	outpos += sizeof(png);
+
+	l = htonl(sizeof(ihdr) - 4); /* "IHDR" is not counted */
+	memcpy(outpos, &l, sizeof(l));
+	outpos += sizeof(l);
+	memcpy(outpos, ihdr, sizeof(ihdr));
+	outpos += sizeof(ihdr);
+	l = crc(ihdr, sizeof(ihdr));
+	memcpy(outpos, &l, sizeof(l));
+	outpos += sizeof(l);
+
+	l = htonl(sizeof(iend) - 4); /* "IEND" is not counted */
+	memcpy(outpos, &l, sizeof(l));
+	outpos += sizeof(l);
+	memcpy(outpos, iend, sizeof(iend));
+	outpos += sizeof(iend);
+	l = crc(iend, sizeof(iend));
+	memcpy(outpos, &l, sizeof(l));
+	outpos += sizeof(l);
+
+	*len = (int)(outpos - image);
+	return image;
+}