sim/erc32: Switched emulated memory to host endian order.

Change data ordering in emulated memory from target order (big endian)
to host order. Improves performance and simplifies most memory
operations. Requires some byte twisting during stores on little
endian hosts (intel). Also removed support for little-endian binaries.

7 files changed, 159 insertions, 210 deletions

diff --git a/sim/erc32/ChangeLog b/sim/erc32/ChangeLog
index 57c1932..109a13b 100644
--- a/sim/erc32/ChangeLog
+++ b/sim/erc32/ChangeLog
@@ -1,3 +1,25 @@
+2015-04-19  Jiri Gaisler  <jiri@gaisler.se>
+
+	* erc32.c (current_target_byte_order): Delete.
+	(fetch_bytes): Remove.
+	(store_bytes): Remove byte twisting.
+	(memory_read, memory_write): Access memory directly.
+	(extract_short, extract_short_signed, extract_byte,
+	extract_byte_signed): New function for for sub-word LD instructions.
+	* exec.c (extract_short, extract_short_signed, extract_byte,
+	extract_byte_signed): New functions.
+	(dispatch_instruction): Update memory reads.
+	* func.c (current_target_byte_order): Delete.
+	(get_regi): Delete little endian handling.
+	(disp_ctrl, dis_mem): Adjust print-out to new data endian.
+	(bfd_load): Delete little endian handling.
+	* interf.c (current_target_byte_order): Delete.
+	(sim_open): Set dinfo to host endian to get correct disassembly.
+	(sim_write, sim_read): Convert endian when gdb reads or writes
+	memory.
+	* sis.c (main): Set endian.
+	* sis.h (EBT): Define.
+
 2015-04-13  Mike Frysinger  <vapier@gentoo.org>
 
 	* configure: Regenerate.
diff --git a/sim/erc32/erc32.c b/sim/erc32/erc32.c
index 7f24fb0..4d4ad04 100644
--- a/sim/erc32/erc32.c
+++ b/sim/erc32/erc32.c
@@ -54,11 +54,6 @@ int dumbio = 0; /* normal, smart, terminal oriented IO by default */
 extern int errmec;
 #endif
 
-/* The target's byte order is big-endian by default until we load a
-   little-endian program.  */
-
-int	current_target_byte_order = BIG_ENDIAN;
-
 #define MEC_WS	0		/* Waitstates per MEC access (0 ws) */
 #define MOK	0
 
@@ -296,11 +291,8 @@ static void	gpt_reload_set (uint32 val);
 static void	timer_ctrl (uint32 val);
 static unsigned char *
 		get_mem_ptr (uint32 addr, uint32 size);
-
-static void	fetch_bytes (int asi, unsigned char *mem,
-			     uint32 *data, int sz);
-
-static void	store_bytes (unsigned char *mem, uint32 *data, int sz);
+static void	store_bytes (unsigned char *mem, uint32 waddr,
+			uint32 *data, int sz, int32 *ws);
 
 extern int	ext_irl;
 
@@ -1524,123 +1516,38 @@ timer_ctrl(val)
 	gpt_start();
 }
 
-
-/* Retrieve data from target memory.  MEM points to location from which
-   to read the data; DATA points to words where retrieved data will be
-   stored in host byte order.  SZ contains log(2) of the number of bytes
-   to retrieve, and can be 0 (1 byte), 1 (one half-word), 2 (one word),
-   or 3 (two words). */
+/* Store data in host byte order.  MEM points to the beginning of the
+   emulated memory; WADDR contains the index the emulated memory,
+   DATA points to words in host byte order to be stored.  SZ contains log(2)
+   of the number of bytes to retrieve, and can be 0 (1 byte), 1 (one half-word),
+   2 (one word), or 3 (two words); WS should return the number of
+   wait-states.  */
 
 static void
-fetch_bytes (asi, mem, data, sz)
-    int		    asi;
-    unsigned char  *mem;
-    uint32	   *data;
-    int		    sz;
+store_bytes (unsigned char *mem, uint32 waddr, uint32 *data, int32 sz,
+	     int32 *ws)
 {
-    if (CURRENT_TARGET_BYTE_ORDER == BIG_ENDIAN
-	|| asi == 8 || asi == 9) {
-	switch (sz) {
-	case 3:
-	    data[1] =  (((uint32) mem[7]) & 0xff) |
-		      ((((uint32) mem[6]) & 0xff) <<  8) |
-		      ((((uint32) mem[5]) & 0xff) << 16) |
-		      ((((uint32) mem[4]) & 0xff) << 24);
-	    /* Fall through to 2 */
-	case 2:
-	    data[0] =  (((uint32) mem[3]) & 0xff) |
-		      ((((uint32) mem[2]) & 0xff) <<  8) |
-		      ((((uint32) mem[1]) & 0xff) << 16) |
-		      ((((uint32) mem[0]) & 0xff) << 24);
-	    break;
-	case 1:
-	    data[0] =  (((uint32) mem[1]) & 0xff) |
-		      ((((uint32) mem[0]) & 0xff) << 8);
-	    break;
+    switch (sz) {
 	case 0:
-	    data[0] = mem[0] & 0xff;
-	    break;
-	    
-	}
-    } else {
-	switch (sz) {
-	case 3:
-	    data[1] = ((((uint32) mem[7]) & 0xff) << 24) |
-		      ((((uint32) mem[6]) & 0xff) << 16) |
-		      ((((uint32) mem[5]) & 0xff) <<  8) |
-		       (((uint32) mem[4]) & 0xff);
-	    /* Fall through to 4 */
-	case 2:
-	    data[0] = ((((uint32) mem[3]) & 0xff) << 24) |
-		      ((((uint32) mem[2]) & 0xff) << 16) |
-		      ((((uint32) mem[1]) & 0xff) <<  8) |
-		       (((uint32) mem[0]) & 0xff);
+	    waddr ^= EBT;
+	    mem[waddr] = *data & 0x0ff;
+	    *ws = mem_ramw_ws + 3;
 	    break;
 	case 1:
-	    data[0] = ((((uint32) mem[1]) & 0xff) <<  8) |
-		       (((uint32) mem[0]) & 0xff);
-	    break;
-	case 0:
-	    data[0] = mem[0] & 0xff;
+#ifdef HOST_LITTLE_ENDIAN
+	    waddr ^= 2;
+#endif
+	    memcpy (&mem[waddr], data, 2);
+	    *ws = mem_ramw_ws + 3;
 	    break;
-	}
-    }
-}
-
-
-/* Store data in target byte order.  MEM points to location to store data;
-   DATA points to words in host byte order to be stored.  SZ contains log(2)
-   of the number of bytes to retrieve, and can be 0 (1 byte), 1 (one half-word),
-   2 (one word), or 3 (two words). */
-
-static void
-store_bytes (mem, data, sz)
-    unsigned char  *mem;
-    uint32	   *data;
-    int		    sz;
-{
-    if (CURRENT_TARGET_BYTE_ORDER == LITTLE_ENDIAN) {
-	switch (sz) {
-	case 3:
-	    mem[7] = (data[1] >> 24) & 0xff;
-	    mem[6] = (data[1] >> 16) & 0xff;
-	    mem[5] = (data[1] >>  8) & 0xff;
-	    mem[4] = data[1] & 0xff;
-	    /* Fall through to 2 */
 	case 2:
-	    mem[3] = (data[0] >> 24) & 0xff;
-	    mem[2] = (data[0] >> 16) & 0xff;
-	    /* Fall through to 1 */
-	case 1:
-	    mem[1] = (data[0] >>  8) & 0xff;
-	    /* Fall through to 0 */
-	case 0:
-	    mem[0] = data[0] & 0xff;
+	    memcpy (&mem[waddr], data, 4);
+	    *ws = mem_ramw_ws;
 	    break;
-	}
-    } else {
-	switch (sz) {
 	case 3:
-	    mem[7] = data[1] & 0xff;
-	    mem[6] = (data[1] >>  8) & 0xff;
-	    mem[5] = (data[1] >> 16) & 0xff;
-	    mem[4] = (data[1] >> 24) & 0xff;
-	    /* Fall through to 2 */
-	case 2:
-	    mem[3] = data[0] & 0xff;
-	    mem[2] = (data[0] >>  8) & 0xff;
-	    mem[1] = (data[0] >> 16) & 0xff;
-	    mem[0] = (data[0] >> 24) & 0xff;
-	    break;
-	case 1:
-	    mem[1] = data[0] & 0xff;
-	    mem[0] = (data[0] >> 8) & 0xff;
-	    break;
-	case 0:
-	    mem[0] = data[0] & 0xff;
+	    memcpy (&mem[waddr], data, 8);
+	    *ws = 2 * mem_ramw_ws + STD_WS;
 	    break;
-	    
-	}
     }
 }
 
@@ -1695,7 +1602,7 @@ memory_read(asi, addr, data, sz, ws)
 #endif
 
     if ((addr >= mem_ramstart) && (addr < (mem_ramstart + mem_ramsz))) {
-	fetch_bytes (asi, &ramb[addr & mem_rammask], data, sz);
+	memcpy (data, &ramb[addr & mem_rammask & ~3], 4);
 	*ws = mem_ramr_ws;
 	return 0;
     } else if ((addr >= MEC_START) && (addr < MEC_END)) {
@@ -1713,7 +1620,7 @@ memory_read(asi, addr, data, sz, ws)
     } else if (era) {
     	if ((addr < 0x100000) || 
 	    ((addr>= 0x80000000) && (addr < 0x80100000))) {
-	    fetch_bytes (asi, &romb[addr & ROM_MASK], data, sz);
+	    memcpy (data, &romb[addr & ROM_MASK & ~3], 4);
 	    *ws = 4;
 	    return 0;
 	} else if ((addr >= 0x10000000) && 
@@ -1724,13 +1631,12 @@ memory_read(asi, addr, data, sz, ws)
 	}
 	
     } else  if (addr < mem_romsz) {
-	    fetch_bytes (asi, &romb[addr], data, sz);
-	    *ws = mem_romr_ws;
-	    return 0;
-
+	memcpy (data, &romb[addr & ~3], 4);
+	*ws = mem_romr_ws;
+	return 0;
 #else
     } else if (addr < mem_romsz) {
-	fetch_bytes (asi, &romb[addr], data, sz);
+	memcpy (data, &romb[addr & ~3], 4);
 	*ws = mem_romr_ws;
 	return 0;
 #endif
@@ -1793,21 +1699,8 @@ memory_write(asi, addr, data, sz, ws)
 		return 1;
 	    }
 	}
-
-	store_bytes (&ramb[addr & mem_rammask], data, sz);
-
-	switch (sz) {
-	case 0:
-	case 1:
-	    *ws = mem_ramw_ws + 3;
-	    break;
-	case 2:
-	    *ws = mem_ramw_ws;
-	    break;
-	case 3:
-	    *ws = 2 * mem_ramw_ws + STD_WS;
-	    break;
-	}
+	waddr = addr & mem_rammask;
+	store_bytes (ramb, waddr, data, sz, ws);
 	return 0;
     } else if ((addr >= MEC_START) && (addr < MEC_END)) {
 	if ((sz != 2) || (asi != 0xb)) {
@@ -1831,7 +1724,7 @@ memory_write(asi, addr, data, sz, ws)
 	((addr < 0x100000) || ((addr >= 0x80000000) && (addr < 0x80100000)))) {
 	    addr &= ROM_MASK;
 	    *ws = sz == 3 ? 8 : 4;
-	    store_bytes (&romb[addr], data, sz);
+	    store_bytes (romb, addr, data, sz, ws);
             return 0;
 	} else if ((addr >= 0x10000000) && 
 		   (addr < (0x10000000 + (512 << (mec_iocr & 0x0f)))) &&
@@ -1847,7 +1740,7 @@ memory_write(asi, addr, data, sz, ws)
 	*ws = mem_romw_ws + 1;
 	if (sz == 3)
 	    *ws += mem_romw_ws + STD_WS;
-	store_bytes (&romb[addr], data, sz);
+	store_bytes (romb, addr, data, sz, ws);
         return 0;
 
 #else
@@ -1858,7 +1751,7 @@ memory_write(asi, addr, data, sz, ws)
 	*ws = mem_romw_ws + 1;
 	if (sz == 3)
             *ws += mem_romw_ws + STD_WS;
-	store_bytes (&romb[addr], data, sz);
+	store_bytes (romb, addr, data, sz, ws);
         return 0;
 
 #endif
diff --git a/sim/erc32/exec.c b/sim/erc32/exec.c
index e6ce6c5..d31032b 100644
--- a/sim/erc32/exec.c
+++ b/sim/erc32/exec.c
@@ -370,6 +370,36 @@ div64 (uint32 n1_hi, uint32 n1_low, uint32 n2, uint32 *result, int msigned)
 }
 
 
+static int
+extract_short (uint32 data, uint32 address)
+{
+    return ((data >> ((2 - (address & 2)) * 8)) & 0xffff);
+}
+
+static int
+extract_short_signed (uint32 data, uint32 address)
+{
+    uint32 tmp = ((data >> ((2 - (address & 2)) * 8)) & 0xffff);
+    if (tmp & 0x8000)
+        tmp |= 0xffff0000;
+    return tmp;
+}
+
+static int
+extract_byte (uint32 data, uint32 address)
+{
+    return ((data >> ((3 - (address & 3)) * 8)) & 0xff);
+}
+
+static int
+extract_byte_signed (uint32 data, uint32 address)
+{
+    uint32 tmp = ((data >> ((3 - (address & 3)) * 8)) & 0xff);
+    if (tmp & 0x80)
+        tmp |= 0xffffff00;
+    return tmp;
+}
+
 int
 dispatch_instruction(sregs)
     struct pstate  *sregs;
@@ -1077,7 +1107,8 @@ dispatch_instruction(sregs)
 		    sregs->trap = TRAP_PRIVI;
 		    break;
 		}
-		sregs->psr = (rs1 ^ operand2) & 0x00f03fff;
+		sregs->psr = (sregs->psr & 0xff000000) |
+			(rs1 ^ operand2) & 0x00f03fff;
 		break;
 	    case WRWIM:
 		if (!(sregs->psr & PSR_S)) {
@@ -1213,8 +1244,10 @@ dispatch_instruction(sregs)
 		else
 		    rdd = &(sregs->g[rd]);
 	    }
-	    mexc = memory_read(asi, address, ddata, 3, &ws);
-	    sregs->hold += ws * 2;
+	    mexc = memory_read (asi, address, ddata, 2, &ws);
+	    sregs->hold += ws;
+	    mexc |= memory_read (asi, address+4, &ddata[1], 2, &ws);
+	    sregs->hold += ws;
 	    sregs->icnt = T_LDD;
 	    if (mexc) {
 		sregs->trap = TRAP_DEXC;
@@ -1252,6 +1285,7 @@ dispatch_instruction(sregs)
 		sregs->trap = TRAP_DEXC;
 		break;
 	    }
+	    data = extract_byte (data, address);
 	    *rdd = data;
 	    data = 0x0ff;
 	    mexc = memory_write(asi, address, &data, 0, &ws);
@@ -1274,8 +1308,10 @@ dispatch_instruction(sregs)
 		sregs->trap = TRAP_DEXC;
 		break;
 	    }
-	    if ((op3 == LDSB) && (data & 0x80))
-		data |= 0xffffff00;
+	    if (op3 == LDSB)
+	        data = extract_byte_signed (data, address);
+	    else
+	        data = extract_byte (data, address);
 	    *rdd = data;
 	    break;
 	case LDSHA:
@@ -1293,8 +1329,10 @@ dispatch_instruction(sregs)
 		sregs->trap = TRAP_DEXC;
 		break;
 	    }
-	    if ((op3 == LDSH) && (data & 0x8000))
-		data |= 0xffff0000;
+	    if (op3 == LDSH)
+	        data = extract_short_signed (data, address);
+	    else
+	        data = extract_short (data, address);
 	    *rdd = data;
 	    break;
 	case LDF:
@@ -1337,8 +1375,10 @@ dispatch_instruction(sregs)
 		    ((sregs->frs2 >> 1) == (rd >> 1)))
 		    sregs->fhold += (sregs->ftime - ebase.simtime);
 	    }
-	    mexc = memory_read(asi, address, ddata, 3, &ws);
-	    sregs->hold += ws * 2;
+	    mexc = memory_read (asi, address, ddata, 2, &ws);
+	    sregs->hold += ws;
+	    mexc |= memory_read (asi, address+4, &ddata[1], 2, &ws);
+	    sregs->hold += ws;
 	    sregs->icnt = T_LDD;
 	    if (mexc) {
 		sregs->trap = TRAP_DEXC;
diff --git a/sim/erc32/func.c b/sim/erc32/func.c
index 479c5ee..9297e07 100644
--- a/sim/erc32/func.c
+++ b/sim/erc32/func.c
@@ -30,10 +30,8 @@
 #include "sim-config.h"
 #include <inttypes.h>
 
-
 #define	VAL(x)	strtoul(x,(char **)NULL,0)
 
-extern int	current_target_byte_order;
 struct disassemble_info dinfo;
 struct pstate   sregs;
 extern struct estate ebase;
@@ -184,18 +182,10 @@ get_regi(struct pstate * sregs, int32 reg, char *buf)
     default:break;
 	}
     }
-    if (current_target_byte_order == BIG_ENDIAN) {
-	buf[0] = (rval >> 24) & 0x0ff;
-	buf[1] = (rval >> 16) & 0x0ff;
-	buf[2] = (rval >> 8) & 0x0ff;
-	buf[3] = rval & 0x0ff;
-    }
-    else {
-	buf[3] = (rval >> 24) & 0x0ff;
-	buf[2] = (rval >> 16) & 0x0ff;
-	buf[1] = (rval >> 8) & 0x0ff;
-	buf[0] = rval & 0x0ff;
-    }
+    buf[0] = (rval >> 24) & 0x0ff;
+    buf[1] = (rval >> 16) & 0x0ff;
+    buf[2] = (rval >> 8) & 0x0ff;
+    buf[3] = rval & 0x0ff;
 }
 
 
@@ -787,15 +777,15 @@ disp_ctrl(sregs)
     struct pstate  *sregs;
 {
 
-    unsigned char           i[4];
+    uint32           i;
 
     printf("\n psr: %08X   wim: %08X   tbr: %08X   y: %08X\n",
 	   sregs->psr, sregs->wim, sregs->tbr, sregs->y);
-    sis_memory_read(sregs->pc, i, 4);
-    printf("\n  pc: %08X = %02X%02X%02X%02X    ", sregs->pc,i[0],i[1],i[2],i[3]);
+    sis_memory_read (sregs->pc, (char *) &i, 4);
+    printf ("\n  pc: %08X = %08X    ", sregs->pc, i);
     print_insn_sparc_sis(sregs->pc, &dinfo);
-    sis_memory_read(sregs->npc, i, 4);
-    printf("\n npc: %08X = %02X%02X%02X%02X    ",sregs->npc,i[0],i[1],i[2],i[3]);
+    sis_memory_read (sregs->npc, (char *) &i, 4);
+    printf ("\n npc: %08X = %08X    ", sregs->npc, i);
     print_insn_sparc_sis(sregs->npc, &dinfo);
     if (sregs->err_mode)
 	printf("\n IU in error mode");
@@ -809,22 +799,25 @@ disp_mem(addr, len)
 {
 
     uint32          i;
-    unsigned char   data[4];
+    union {
+	    unsigned char u8[4];
+	    uint32 u32;
+    } data;
     uint32          mem[4], j;
     char           *p;
 
     for (i = addr & ~3; i < ((addr + len) & ~3); i += 16) {
 	printf("\n %8X  ", i);
 	for (j = 0; j < 4; j++) {
-	    sis_memory_read((i + (j * 4)), data, 4);
-	    printf("%02x%02x%02x%02x  ", data[0],data[1],data[2],data[3]);
-	    mem[j] = *((int *) &data);
+	    sis_memory_read ((i + (j * 4)), data.u8, 4);
+	    printf ("%08x  ", data.u32);
+	    mem[j] = data.u32;
 	}
 	printf("  ");
 	p = (char *) mem;
 	for (j = 0; j < 16; j++) {
-	    if (isprint(p[j]))
-		putchar(p[j]);
+	    if (isprint (p[j ^ EBT]))
+		putchar (p[j ^ EBT]);
 	    else
 		putchar('.');
 	}
@@ -839,11 +832,14 @@ dis_mem(addr, len, info)
     struct disassemble_info *info;
 {
     uint32          i;
-    unsigned char   data[4];
+    union {
+	    unsigned char u8[4];
+	    uint32 u32;
+    } data;
 
     for (i = addr & -3; i < ((addr & -3) + (len << 2)); i += 4) {
-	sis_memory_read(i, data, 4);
-	printf(" %08x  %02x%02x%02x%02x  ", i, data[0],data[1],data[2],data[3]);
+	sis_memory_read (i, data.u8, 4);
+	printf (" %08x  %08x  ", i, data.u32);
 	print_insn_sparc_sis(i, info);
         if (i >= 0xfffffffc) break;
 	printf("\n");
@@ -1041,6 +1037,7 @@ bfd_load (const char *fname)
     asection       *section;
     bfd            *pbfd;
     const bfd_arch_info_type *arch;
+    int            i;
 
     pbfd = bfd_openr(fname, 0);
 
@@ -1054,14 +1051,6 @@ bfd_load (const char *fname)
     }
 
     arch = bfd_get_arch_info (pbfd);
-    if (bfd_little_endian (pbfd) || arch->mach == bfd_mach_sparc_sparclite_le)
-        current_target_byte_order = LITTLE_ENDIAN;
-    else
-	current_target_byte_order = BIG_ENDIAN;
-    if (sis_verbose)
-	printf("file %s is %s-endian.\n", fname,
-	       current_target_byte_order == BIG_ENDIAN ? "big" : "little");
-
     if (sis_verbose)
 	printf("loading %s:", fname);
     for (section = pbfd->sections; section; section = section->next) {
@@ -1093,10 +1082,7 @@ bfd_load (const char *fname)
 					      sizeof (marker));
 		    if (strncmp (marker.signature, "DaTa", 4) == 0)
 		      {
-			if (current_target_byte_order == BIG_ENDIAN)
-			  section_address = bfd_getb32 (marker.sdata);
-			else
-			  section_address = bfd_getl32 (marker.sdata);
+			section_address = bfd_getb32 (marker.sdata);
 		      }
 		}
 	    }
@@ -1121,7 +1107,8 @@ bfd_load (const char *fname)
 
 		    bfd_get_section_contents(pbfd, section, buffer, fptr, count);
 
-		    sis_memory_write(section_address, buffer, count);
+		    for (i = 0; i < count; i++)
+			sis_memory_write ((section_address + i) ^ EBT, &buffer[i], 1);
 
 		    section_address += count;
 		    fptr += count;
diff --git a/sim/erc32/interf.c b/sim/erc32/interf.c
index 59fb635..235af8b 100644
--- a/sim/erc32/interf.c
+++ b/sim/erc32/interf.c
@@ -40,7 +40,6 @@ extern struct disassemble_info dinfo;
 extern struct pstate sregs;
 extern struct estate ebase;
 
-extern int	current_target_byte_order;
 extern int      ctrl_c;
 extern int      nfp;
 extern int      ift;
@@ -252,7 +251,11 @@ sim_open (kind, callback, abfd, argv)
     sregs.freq = freq ? freq : 15;
     termsave = fcntl(0, F_GETFL, 0);
     INIT_DISASSEMBLE_INFO(dinfo, stdout,(fprintf_ftype)fprintf);
+#ifdef HOST_LITTLE_ENDIAN
+    dinfo.endian = BFD_ENDIAN_LITTLE;
+#else
     dinfo.endian = BFD_ENDIAN_BIG;
+#endif
     reset_all();
     ebase.simtime = 0;
     init_sim();
@@ -311,14 +314,10 @@ sim_store_register(sd, regno, value, length)
     unsigned char  *value;
     int length;
 {
-    /* FIXME: Review the computation of regval.  */
     int regval;
-    if (current_target_byte_order == BIG_ENDIAN)
-	regval = (value[0] << 24) | (value[1] << 16)
+
+    regval = (value[0] << 24) | (value[1] << 16)
 		 | (value[2] << 8) | value[3];
-    else
-	regval = (value[3] << 24) | (value[2] << 16)
-		 | (value[1] << 8) | value[0];
     set_regi(&sregs, regno, regval);
     return length;
 }
@@ -336,23 +335,25 @@ sim_fetch_register(sd, regno, buf, length)
 }
 
 int
-sim_write(sd, mem, buf, length)
-     SIM_DESC sd;
-    SIM_ADDR             mem;
-    const unsigned char  *buf;
-    int             length;
+sim_write (SIM_DESC sd, SIM_ADDR mem, const unsigned char *buf, int length)
 {
-    return sis_memory_write (mem, buf, length);
+    int i, len;
+
+    for (i = 0; i < length; i++) {
+	sis_memory_write ((mem + i) ^ EBT, &buf[i], 1);
+    }
+    return length;
 }
 
 int
-sim_read(sd, mem, buf, length)
-     SIM_DESC sd;
-     SIM_ADDR mem;
-     unsigned char *buf;
-     int length;
+sim_read (SIM_DESC sd, SIM_ADDR mem, unsigned char *buf, int length)
 {
-    return sis_memory_read (mem, buf, length);
+    int i, len;
+
+    for (i = 0; i < length; i++) {
+	sis_memory_read ((mem + i) ^ EBT, &buf[i], 1);
+    }
+    return length;
 }
 
 void
diff --git a/sim/erc32/sis.c b/sim/erc32/sis.c
index 6259067..92880e1 100644
--- a/sim/erc32/sis.c
+++ b/sim/erc32/sis.c
@@ -223,7 +223,11 @@ main(argc, argv)
     sregs.freq = freq;
 
     INIT_DISASSEMBLE_INFO(dinfo, stdout, (fprintf_ftype) fprintf);
+#ifdef HOST_LITTLE_ENDIAN
+    dinfo.endian = BFD_ENDIAN_LITTLE;
+#else
     dinfo.endian = BFD_ENDIAN_BIG;
+#endif
 
     termsave = fcntl(0, F_GETFL, 0);
     using_history();
diff --git a/sim/erc32/sis.h b/sim/erc32/sis.h
index ae39ad1..99ae347 100644
--- a/sim/erc32/sis.h
+++ b/sim/erc32/sis.h
@@ -28,8 +28,10 @@
 
 #if WITH_HOST_BYTE_ORDER == BIG_ENDIAN
 #define HOST_BIG_ENDIAN
+#define EBT 0
 #else
 #define HOST_LITTLE_ENDIAN
+#define EBT 3
 #endif
 
 #define I_ACC_EXC 1