Added support for version 1.20 of the 86F format;

Hopefully made the 86F handler for the FDC READ TRACK command work correctly.

src/disc_random.c

@@ -0,0 +1,66 @@
+/* Better random number generator by Battler. */
+
+#include <assert.h>
+#include <stdio.h>
+
+#include <stdint.h>
+
+#include <inttypes.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+
+#include "disc_random.h"
+
+dword preconst = 0x6ED9EBA1;
+
+static __inline__ uint32_t rotl32c (uint32_t x, uint32_t n)
+{
+  assert (n<32);
+  return (x<<n) | (x>>(-n&31));
+}
+
+static __inline__ uint32_t rotr32c (uint32_t x, uint32_t n)
+{
+  assert (n<32);
+  return (x>>n) | (x<<(-n&31));
+}
+
+#define ROTATE_LEFT rotl32c
+
+#define ROTATE_RIGHT rotr32c
+
+static __inline__ unsigned long long rdtsc(void)
+{
+    unsigned hi, lo;
+    __asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
+    return ( (unsigned long long)lo)|( ((unsigned long long)hi)<<32 );
+}
+
+static UINT4 RDTSC(void)
+{
+	return (UINT4) (rdtsc());
+}
+
+static void disc_random_twist(uint32_t *val)
+{
+	*val = ROTATE_LEFT(*val, rand() % 32);
+	*val ^= 0x5A827999;
+	*val = ROTATE_RIGHT(*val, rand() % 32);
+	*val ^= 0x4ED32706;
+}
+
+uint8_t disc_random_generate()
+{
+	uint16_t r = 0;
+	r = (rand() ^ ROTATE_LEFT(preconst, rand() % 32)) % 256;
+	disc_random_twist(&preconst);
+	return (r & 0xff);
+}
+
+void disc_random_init()
+{
+	dword seed = RDTSC();
+	srand(seed);
+	return;
+}