X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=babel%2Fadrift.c;fp=babel%2Fadrift.c;h=3718d6ae4bfc02f1dd8a5964174cec595dcf58a9;hb=6fd0347f330cb24ef6145662023053a1c0f81a64;hp=0000000000000000000000000000000000000000;hpb=7d14a66ee234db0898de6fabb8f850ebc4bb733a;p=projects%2Fchimara%2Fchimara.git

diff --git a/babel/adrift.c b/babel/adrift.c
new file mode 100644
index 0000000..3718d6a
--- /dev/null
+++ b/babel/adrift.c
@@ -0,0 +1,89 @@
+/* adrift.c  Treaty of Babel module for Adrift files
+ *
+ * PROVISIONAL - Hold for someone else
+ *
+ * This file depends on treaty_builder.h
+ *
+ * This file is public domain, but note that any changes to this file
+ * may render it noncompliant with the Treaty of Babel
+ */
+
+#define FORMAT adrift
+#define HOME_PAGE "http://www.adrift.org.uk"
+#define FORMAT_EXT ".taf"
+#define NO_METADATA
+#define NO_COVER
+
+#include "treaty_builder.h"
+
+#include <stdio.h>
+#include <limits.h>
+#include <stdlib.h>
+
+/* VB RNG constants */
+#define  VB_RAND1      0x43FD43FD
+#define  VB_RAND2      0x00C39EC3
+#define  VB_RAND3      0x00FFFFFF
+#define  VB_INIT       0x00A09E86
+static int32 vbr_state;
+
+/*
+  Unobfuscates one byte from a taf file. This should be called on each byte
+  in order, as the ADRIFT obfuscation function is stately.
+
+  The de-obfuscation algorithm works by xoring the byte with the next
+  byte in the sequence produced by the Visual Basic pseudorandom number
+  generator, which is simulated here.
+*/
+static unsigned char taf_translate (unsigned char c)
+{
+ int32 r;
+
+ vbr_state = (vbr_state*VB_RAND1+VB_RAND2) & VB_RAND3;
+ r=UCHAR_MAX * (unsigned) vbr_state;
+ r/=((unsigned) VB_RAND3)+1;
+ return r^c;
+}
+
+static int32 get_story_file_IFID(void *story_file, int32 extent, char *output, int32 output_extent)
+{
+ int adv;
+ unsigned char buf[4];
+ unsigned char *sf=(unsigned char *)story_file;
+ vbr_state=VB_INIT;
+
+ if (extent <12) return INVALID_STORY_FILE_RV;
+
+ buf[3]=0;
+ /* Burn the first 8 bytes of translation */
+ for(adv=0;adv<8;adv++) taf_translate(0);
+ /* Bytes 8-11 contain the Adrift version number in the formay N.NN */
+ buf[0]=taf_translate(sf[8]);
+ taf_translate(0);
+ buf[1]=taf_translate(sf[10]);
+ buf[2]=taf_translate(sf[11]);
+ adv=atoi((char *) buf);
+ ASSERT_OUTPUT_SIZE(12);
+ sprintf(output,"ADRIFT-%03d-",adv);
+ return INCOMPLETE_REPLY_RV;
+
+}
+
+/* The claim algorithm for ADRIFT is to unobfuscate the first
+   seven bytes, and check for the word "Version".
+   It seems fairly unlikely that the obfuscated form of that
+   word would occur in the wild
+*/
+static int32 claim_story_file(void *story_file, int32 extent)
+{
+ unsigned char buf[8];
+ int i;
+ unsigned char *sf=(unsigned char *)story_file;
+ buf[7]=0;
+ vbr_state=VB_INIT;
+ if (extent<12) return INVALID_STORY_FILE_RV;
+ for(i=0;i<7;i++) buf[i]=taf_translate(sf[i]);
+ if (strcmp((char *)buf,"Version")) return INVALID_STORY_FILE_RV;
+ return VALID_STORY_FILE_RV;
+
+}