Update from Chris Johns <cjohns@awa.com.au> to add better support for

68000 class CPUs.

3 files changed, 56 insertions, 22 deletions

diff --git a/c/src/exec/score/cpu/m68k/cpu.c b/c/src/exec/score/cpu/m68k/cpu.c
index f57fae6685..1c43c23379 100644
--- a/c/src/exec/score/cpu/m68k/cpu.c
+++ b/c/src/exec/score/cpu/m68k/cpu.c
@@ -31,6 +31,21 @@ void _CPU_Initialize(
   void      (*thread_dispatch)      /* ignored on this CPU */
 )
 {
+#if ( M68K_HAS_VBR == 0 )
+  /* fill the isr redirect table with the code to place the format/id
+     onto the stack */
+
+  unsigned32 slot;
+
+  for (slot = 0; slot < CPU_INTERRUPT_NUMBER_OF_VECTORS; slot++)
+  {
+    _CPU_ISR_jump_table[slot].move_a7 = M68K_MOVE_A7;
+    _CPU_ISR_jump_table[slot].format_id = slot << 2;
+    _CPU_ISR_jump_table[slot].jmp = M68K_JMP;
+    _CPU_ISR_jump_table[slot].isr_handler = (unsigned32) 0xDEADDEAD;
+  }
+#endif /* M68K_HAS_VBR */
+
   _CPU_Table = *cpu_table;
 }
 
@@ -63,12 +78,13 @@ void _CPU_ISR_install_raw_handler(
 
   m68k_get_vbr( interrupt_table );
 
-#if ( M68K_HAS_VBR == 1)
   *old_handler = interrupt_table[ vector ];
+
+#if ( M68K_HAS_VBR == 1 )
   interrupt_table[ vector ] = new_handler;
 #else
-  *old_handler = *(proc_ptr *)( (int)interrupt_table+ (int)vector*6-10);
-  *(proc_ptr *)( (int)interrupt_table+ (int)vector*6-10) = new_handler;
+  _CPU_ISR_jump_table[vector].isr_handler = (unsigned32) new_handler;
+  interrupt_table[ vector ] = (proc_ptr) &_CPU_ISR_jump_table[vector];
 #endif /* M68K_HAS_VBR */
 }
 
diff --git a/c/src/exec/score/cpu/m68k/cpu.h b/c/src/exec/score/cpu/m68k/cpu.h
index 59f8d3d4b7..48caa7a0d7 100644
--- a/c/src/exec/score/cpu/m68k/cpu.h
+++ b/c/src/exec/score/cpu/m68k/cpu.h
@@ -139,10 +139,37 @@ typedef struct {
 
 /* variables */
 
-SCORE_EXTERN void               *_CPU_Interrupt_stack_low;
-SCORE_EXTERN void               *_CPU_Interrupt_stack_high;
+SCORE_EXTERN void                   *_CPU_Interrupt_stack_low;
+SCORE_EXTERN void                   *_CPU_Interrupt_stack_high;
+
+extern char                         _VBR[]; 
+
+#if ( M68K_HAS_VBR == 0 )
+
+/*
+ * Table of ISR handler entries that resides in RAM. The FORMAT/ID is
+ * pushed onto the stack. This is not is the same order as VBR processors.
+ * The ISR handler takes the format and uses it for dispatching the user
+ * handler.
+ *
+ * FIXME : should be moved to below CPU_INTERRUPT_NUMBER_OF_VECTORS
+ *
+ */
+
+typedef struct {
+  unsigned16 move_a7;            /* move #FORMAT_ID,%a7@- */
+  unsigned16 format_id;
+  unsigned16 jmp;                /* jmp  _ISR_Handlers */
+  unsigned32 isr_handler;
+} _CPU_ISR_handler_entry;
+
+#define M68K_MOVE_A7 0x3F3C
+#define M68K_JMP     0x4EF9
+
       /* points to jsr-exception-table in targets wo/ VBR register */
-extern char                      _VBR[]; 
+SCORE_EXTERN _CPU_ISR_handler_entry _CPU_ISR_jump_table[256]; 
+
+#endif /* M68K_HAS_VBR */
 
 /* constants */
 
diff --git a/c/src/exec/score/cpu/m68k/cpu_asm.s b/c/src/exec/score/cpu/m68k/cpu_asm.s
index 8cce6e5ca5..255aeb23f7 100644
--- a/c/src/exec/score/cpu/m68k/cpu_asm.s
+++ b/c/src/exec/score/cpu/m68k/cpu_asm.s
@@ -122,9 +122,9 @@ norst:  frestore a0@+                     | restore the fp state frame
 .set PC_OFFSET,    2                     | Program Counter offset
 .set FVO_OFFSET,   6                     | Format/vector offset
 #else
-.set JSR_OFFSET,   0                     | return address from jsr table
-.set SR_OFFSET,    4
-.set PC_OFFSET,    6
+.set SR_OFFSET,    2                     | Status register offset
+.set PC_OFFSET,    4                     | Program Counter offset
+.set FVO_OFFSET,   0                     | Format/vector offset placed in the stack
 #endif /* M68K_HAS_VBR */
  
 .set SAVED,        16                    | space for saved registers
@@ -144,17 +144,8 @@ SYM (_ISR_Handler):
  *  to switch to the software maintained interrupt stack.
  */
 
-#if ( M68K_HAS_VBR == 0)
-        movel   a7@(SAVED+JSR_OFFSET),d0 | assume the exception table at 0x0000
-        addql   #6,d0                    | points to a jump table (jsr) in RAM
-        subl    #_VBR,d0                 | VBR is the location of the jump table
-        divs    #3,d0
-        lsll    #1,d0
-        extl    d0
-#else
         movew   a7@(SAVED+FVO_OFFSET),d0 | d0 = F/VO
         andl    #0x0fff,d0               | d0 = vector offset in vbr
-#endif
 
 #if ( M68K_HAS_PREINDEXING == 1 )
         movel   @( SYM (_ISR_Vector_table),d0:w:1),a0| fetch the ISR
@@ -212,8 +203,8 @@ bframe: clrl    SYM (_ISR_Signals_to_thread_executing)
 #endif
 
 exit:   moveml  a7@+,d0-d1/a0-a1         | restore d0-d1,a0-a1
-#if ( M68K_HAS_VBR == 0)
-        addql   #4,a7                    | pop vector address
+#if ( M68K_HAS_VBR == 0 )
+        addql   #2,a7                    | pop format/id
 #endif /* M68K_HAS_VBR */
         rte                              | return to thread
                                          |   OR _Isr_dispatch
@@ -237,7 +228,7 @@ SYM (_ISR_Dispatch):
         movml   d0-d1/a0-a1,a7@-
         jsr     SYM (_Thread_Dispatch)
         movml   a7@+,d0-d1/a0-a1
-#if ( M68K_HAS_VBR == 0)
-        addql   #4,a7                    | pop vector address
+#if ( M68K_HAS_VBR == 0 )
+        addql   #2,a7                    | pop format/id
 #endif /* M68K_HAS_VBR */
         rte