Adjust exception error messages to show correct address.

Detail:
  Add offset parameter to DumpyTheRegisters in R4
  Shuffle internal register use up one
  Set R4 to offset before calling.
  Arbitrary offset of 0 for unreachable address exception handler.

Admin:
  Tested in RPCEmu.

s/Middle

@@ -619,6 +619,7 @@ PrintErrorString
 DumpyTheRegisters  ROUT
 ; R0 points at r8 in register dump. r0-r7, PC, PSR saved
 ; R1 is PSR
+; R4 is offset from saved PC for error message
 ; R14 points at error block
 ; In ABT32 or UND32
         MOV     R7, R14                 ; put error address into unbanked register
@@ -675,9 +676,9 @@ UNDEF1
 
         ; Check that ExceptionDump is safe to use
         Push    "R7"                    ; Preserve error ptr
-        LDR     R4, =ZeroPage
+        LDR     R5, =ZeroPage
         MOV     R3, R0
-        LDR     R1, [R4, #ExceptionDump]
+        LDR     R1, [R5, #ExceptionDump]
         MOV     R0, #24
         ADD     R2, R1, #17*4
         ; Must be SVC-writable, user+SVC readable, word aligned
@@ -697,15 +698,15 @@ UNDEF1
         Pull    "R14"                   ; Restore error ptr
 
         ; Copy the dump from the stack to ExceptionDump
-        LDR     R0, [R4, #ExceptionDump]
-        LDMIA   R3!, {R1-R2,R4-R9}      ; R0-R7
-        STMIA   R0!, {R1-R2,R4-R9}
-        LDMIA   R3, {R1-R2,R4-R10}      ; R8-R15, PSR
-        STMIA   R0, {R1-R2,R4-R10}
+        LDR     R0, [R5, #ExceptionDump]
+        LDMIA   R3!, {R1-R2,R5-R10}     ; R0-R7
+        STMIA   R0!, {R1-R2,R5-R10}
+        LDMIA   R3, {R1-R2,R5-R11}      ; R8-R15, PSR
+        STMIA   R0, {R1-R2,R5-R11}
 
         SUB     R0, R0, #8*4
                                         ; try and put back user R10-R12
-        Push    "R4-R6"                 ; for error handler to find on stack
+        Push    "R5-R7"                 ; for error handler to find on stack
         LDR     R1, [R0, #15*4]
         Push    R1
 
@@ -735,6 +736,7 @@ UNDEF1
         LDR     R0, =ZeroPage
         LDR     R0, [R0, #ExceptionDump]
         LDR     R0, [R0, #15*4]         ; saved PC
+        SUB     R0, R0, R4
         SWI     XOS_ConvertHex8
 
       [ International
@@ -834,6 +836,7 @@ UNDEF ROUT
         MRS     R1, SPSR
         STR     R1, [R14, #(16-8)*4]            ; save PSR
         MOV     R0, R14
+        MOV     R4, #4
         BL      DumpyTheRegisters
         MakeErrorBlock UndefinedInstruction
 
@@ -847,6 +850,7 @@ ABORTP ROUT
         MRS     R1, SPSR
         STR     R1, [R14, #(16-8)*4]            ; save PSR
         MOV     R0, R14
+        MOV     R4, #4
         BL      DumpyTheRegisters
         MakeErrorBlock InstructionAbort
 
@@ -860,6 +864,7 @@ ABORTD ROUT
         MRS     R1, SPSR
         STR     R1, [R14, #(16-8)*4]            ; save PSR
         MOV     R0, R14
+        MOV     R4, #8
         BL      DumpyTheRegisters
         MakeErrorBlock DataAbort
 
@@ -875,6 +880,7 @@ ADDREX ROUT
         MRS     R1, SPSR
         STR     R1, [R14, #(16-8)*4]            ; save PSR
         MOV     R0, R14
+        MOV     R4, #0
         BL      DumpyTheRegisters
         MakeErrorBlock AddressException
 
@@ -921,6 +927,7 @@ Branch0_FromTrampoline
         ADD     R0, R0, #8*4
 
         ADR     R7, ErrorBlock_BranchThrough0
+        MOV     R4, #0
         B       UNDEF1
         MakeErrorBlock BranchThrough0