From 3197705f493ca75933a4d5bdeae9bda2e2dd040b Mon Sep 17 00:00:00 2001
From: aap <aap@papnet.eu>
Date: Tue, 31 Jan 2017 00:47:17 +0100
Subject: [PATCH] ld6: added RIM10B loader to RIM format

---
 tools/ld6.c        | 45 +++++++++++++++++++++++++++++----------------
 tools/pdp6common.c | 27 +++++++++++++++++++++++++++
 tools/pdp6common.h |  3 +++
 3 files changed, 59 insertions(+), 16 deletions(-)

diff --git a/tools/ld6.c b/tools/ld6.c
index d989b66..9ebb390 100644
--- a/tools/ld6.c
+++ b/tools/ld6.c
@@ -414,7 +414,8 @@ saverim(const char *filename)
 	fclose(out);
 }
 
-/* Saves in RIM10 format. Only one block is written.
+/* Saves in RIM10 format. Begins with the RIM10B loader,
+ *  after that only one block is written.
  *	IOWD count,origin
  *	word
  *	...
@@ -423,6 +424,23 @@ saverim(const char *filename)
  *	...
  *	JRST start
  */
+word rim10b[] = {
+	0777762000000,
+	0710600000060,
+	0541400000004,
+	0710740000010,
+	0254000000003,
+	0710470000007,
+	0256010000007,
+	0256010000012,
+	0364400000000,
+	0312740000016,
+	0270756000001,
+	0331740000016,
+	0254200000001,
+	0253700000003,
+	0254000000002,
+};
 void
 saverim10(const char *filename)
 {
@@ -434,6 +452,10 @@ saverim10(const char *filename)
 	out = mustopen(filename, "wb");
 	checksum = 0;
 
+	/* write RIM10B loader */
+	for(i = 0; i < 017; i++)
+		writew(rim10b[i], out);
+
 	w = fw(-(locmax+1-locmin), locmin-1);
 	writew(w, out);	/* IOWD count,origin */
 	checksum += w;
@@ -441,23 +463,14 @@ saverim10(const char *filename)
 		writew(mem[i], out);
 		checksum += mem[i];
 	}
-	writew(-checksum, out);
+	checksum &= 0777777777777;
+//	writew(-checksum, out);	/* this was apparently wrong? */
+	writew(checksum, out);
 
 	writew(fw(0254000, start), out);	/* JRST start */
 	fclose(out);
 }
 
-void
-writeww(word w, FILE *fp)
-{
-	unsigned char c;
-	putc((w >> 29) & 0177, fp);
-	putc((w >> 22) & 0177, fp);
-	putc((w >> 15) & 0177, fp);
-	putc((w >> 8) & 0177, fp);
-	putc((w>>1) & 0177 | (w & 1) << 7, fp);
-}
-
 /* Saves in SAV format. Only one block is saved.
  *	IOWD count,origin
  *	word
@@ -472,10 +485,10 @@ savesav(const char *filename)
 	FILE *out;
 	hword i;
 	out = mustopen(filename, "wb");
-	writeww(fw(-(locmax+1-locmin), locmin-1), out);	/* IOWD count,origin */
+	writewbak(fw(-(locmax+1-locmin), locmin-1), out);	/* IOWD count,origin */
 	for(i = locmin; i <= locmax; i++)
-		writeww(mem[i], out);
-	writeww(fw(0254000, start), out);	/* JRST start */
+		writewbak(mem[i], out);
+	writewbak(fw(0254000, start), out);	/* JRST start */
 	fclose(out);
 }
 
diff --git a/tools/pdp6common.c b/tools/pdp6common.c
index 9c274c2..b7d697a 100644
--- a/tools/pdp6common.c
+++ b/tools/pdp6common.c
@@ -11,6 +11,7 @@ hword right(word w) { return w & 0777777; }
 word negw(word w) { return (~w + 1) & 0777777777777; }
 int isneg(word w) { return !!(w & 0400000000); }
 
+/* write word in rim format */
 void
 writew(word w, FILE *fp)
 {
@@ -37,6 +38,32 @@ readw(FILE *fp)
 	return w;
 }
 
+/* write word in backup format. This is what pdp10-ka expects. */
+void
+writewbak(word w, FILE *fp)
+{
+	unsigned char c;
+	putc((w >> 29) & 0177, fp);
+	putc((w >> 22) & 0177, fp);
+	putc((w >> 15) & 0177, fp);
+	putc((w >> 8) & 0177, fp);
+	putc((w>>1) & 0177 | (w & 1) << 7, fp);
+}
+
+word
+readwbak(FILE *fp)
+{
+	char buf[5];
+	if(fread(buf, 1, 5, fp) != 5)
+		return ~0;
+	return (word)buf[0] << 29 |
+	       (word)buf[1] << 22 |
+	       (word)buf[2] << 15 |
+	       (word)buf[3] << 8 |
+	       ((word)buf[4]&0177) << 1 |
+	       ((word)buf[4]&0200) >> 7;
+}
+
 /* decompose a double into sign, exponent and mantissa */
 void
 decompdbl(double d, int *s, word *e, uint64_t *m)
diff --git a/tools/pdp6common.h b/tools/pdp6common.h
index d1ef412..ddda1c6 100644
--- a/tools/pdp6common.h
+++ b/tools/pdp6common.h
@@ -7,8 +7,11 @@ hword left(word w);
 hword right(word w);
 word negw(word w);
 int isneg(word w);
+
 void writew(word w, FILE *fp);
 word readw(FILE *fp);
+void writewbak(word w, FILE *fp);
+word readwbak(FILE *fp);
 
 void decompdbl(double d, int *s, word *e, uint64_t *m);
 word dtopdp(double d);