[bug-mes] [PATCH] Support ARM (instruction-granularity) displacements.

[Danny Milosavljevic]

---
 hex2_linker.c | 37 +++++++++++++++++++++++++++++++------
 1 file changed, 31 insertions(+), 6 deletions(-)

diff --git a/hex2_linker.c b/hex2_linker.c
index 80ce2a2..1ddcf79 100644
--- a/hex2_linker.c
+++ b/hex2_linker.c
@@ -218,7 +218,36 @@ int Architectural_displacement(int target, int base)
        if(0 == Architecture) return (target - base);
        else if(1 == Architecture) return (target - base);
        else if(2 == Architecture) return (target - base);
-       else if(40 == Architecture) return (target - base);
+       else if(40 == Architecture)
+       {
+               /* Note: Branch displacements on ARM are in number of
+                  instructions to skip, basically. */
+               if (target < 0)
+               {
+                       file_print("Architectural_displacement of negative 
target is not implemented\n", stderr);
+                       exit(EXIT_FAILURE);
+               }
+               if (base < 0)
+               {
+                       file_print("Architectural_displacement of negative base 
is not implemented\n", stderr);
+                       exit(EXIT_FAILURE);
+               }
+               if (target & 3)
+               {
+                       file_print("Unaligned branch target, aborting\n", 
stderr);
+                       exit(EXIT_FAILURE);
+               }
+               /* base already moved because of the opcode part of the
+                  branch instruction, so calculate from the previous
+                  position. */
+               base &= ~3;
+               /* The "fetch" stage already moved forward by 8 from the
+                  beginning of the instruction because it is already
+                  prefetching the next instruction.
+                  Compensate for it by subtracting the space for
+                  two instructions (including the branch instruction). */
+               return ((target - base) >> 2) - 2;
+       }
 
        file_print("Unknown Architecture, aborting before harm is done\n", 
stderr);
        exit(EXIT_FAILURE);
@@ -261,11 +290,7 @@ void storePointer(char ch, FILE* source_file)
        displacement = Architectural_displacement(target, base);
 
        /* output calculated difference */
-       if('!' == ch)
-       {
-               if(40 == Architecture) outputPointer(displacement - 7, 1); /* 
Deal with ! */
-               else outputPointer(displacement, 1); /* Deal with ! */
-       }
+       if('!' == ch) outputPointer(displacement, 1); /* Deal with ! */
        else if('$' == ch) outputPointer(target, 2); /* Deal with $ */
        else if('@' == ch) outputPointer(displacement, 2); /* Deal with @ */
        else if('~' == ch) outputPointer(displacement, 3); /* Deal with ~ */