add sign extension for immediate mode add (imm5)

this part of code converts 5bit numbers to 8bit numbers in case of imm5 type of add, preserving sign when negative
2022-02-01 00:20:03 +01:00
parent f7650aaa2e
commit ae4e0bb5ef
1 changed files with 8 additions and 3 deletions
@@ -96,9 +96,14 @@ enum flags {
    FL_N = 1 << 2,    // Negative
 };

-
-
-
+/* sign extension for immediate add mode (imm5[0:4])
+transforms 5bit number to 8bit number preserving sign*/
+uint16_t sign_extend(uint16_t bin, int bit_count) {
+    if((bin >> (bit_count - 1)) & 1) {
+        bin |= (0xFFFF << bit_count);
+    }
+    return bin;
+}

 /* main loop */
 int main(int argc, const char* argv[]) {