opcodes/cgen: Rework calculation of shift when inserting fields

[thirdparty/binutils-gdb.git] / opcodes / mep-ibld.c

diff --git a/opcodes/mep-ibld.c b/opcodes/mep-ibld.c
index d1e33fa730f728241b6ef562fd06a9795597046e..0faf9481d9de4ce444cdff61ddf01d571ef0a1a5 100644 (file)
--- a/opcodes/mep-ibld.c
+++ b/opcodes/mep-ibld.c
@@ -207,12 +207,19 @@ insert_normal (CGEN_CPU_DESC cd,
 #if CGEN_INT_INSN_P
 
   {
-    int shift;
+    int shift_within_word, shift_to_word, shift;
 
+    /* How to shift the value to BIT0 of the word.  */
+    shift_to_word = total_length - (word_offset + word_length);
+
+    /* How to shift the value to the field within the word.  */
     if (CGEN_INSN_LSB0_P)
-      shift = (word_offset + start + 1) - length;
+      shift_within_word = start + 1 - length;
     else
-      shift = total_length - (word_offset + start + length);
+      shift_within_word = word_length - start - length;
+
+    /* The total SHIFT, then mask in the value.  */
+    shift = shift_to_word + shift_within_word;
     *buffer = (*buffer & ~(mask << shift)) | ((value & mask) << shift);
   }