From d714a52cb6a96e4350bde8b39b6a58daa0afa629 Mon Sep 17 00:00:00 2001
From: James Stine <james.stine@okstate.edu>
Date: Tue, 1 Oct 2024 13:07:28 -0500
Subject: [PATCH] update fpcalc.c to match book and lex 0x or x prefix for
 inputs.  Also improve the output for f128 to match half/single/double

---
 examples/fp/fpcalc/fpcalc.c | 42 ++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/examples/fp/fpcalc/fpcalc.c b/examples/fp/fpcalc/fpcalc.c
index 8264b1442..719fc72a6 100644
--- a/examples/fp/fpcalc/fpcalc.c
+++ b/examples/fp/fpcalc/fpcalc.c
@@ -224,8 +224,15 @@ __uint128_t strtoul128(char *num, int base) {
 }
 
 __uint128_t parseNum(char *num) {
-//  uint64_t result;
+  //  uint64_t result;
   __uint128_t result;
+
+  // Ensure input starts with "0x" or "x"
+  if (!(num[0] == '0' && num[1] == 'x') && !(num[0] == 'x')) {
+    printf("Error: Input must start with '0x' or 'x'\n");
+    exit(1);
+  }
+
   int size; // size of operands in bytes (2= half, 4=single, 8 = double)
   if (strlen(num) < 8) size = 2;
   else if (strlen(num) < 16) size = 4;
@@ -244,7 +251,34 @@ __uint128_t parseNum(char *num) {
     opSize = size;
     //printf ("Operand size is %d\n", opSize);
   }
-  result = (__uint128_t)strtoul128(num, 16);
+
+  // Add to handle either input preference                                                                                                                                                        
+  // Strip the "x" or "0x" prefixes if present                                                                                                                                                    
+  if (num[0] == 'x' || (num[0] == '0' && num[1] == 'x')) {
+    num += (num[0] == 'x') ? 1 : 2;
+  }
+
+  if (strlen(num) <= 16) {
+    result = (__uint128_t)strtoull(num, NULL, 16);
+  }
+  else {
+    while (*num) {
+      int value;
+      if (*num >= '0' && *num <= '9')
+        value = *num - '0';
+      else if (*num >= 'a' && *num <= 'f')
+        value = *num - 'a' + 10;
+      else if (*num >= 'A' && *num <= 'F')
+        value = *num - 'A' + 10;
+      else {
+        printf("Error: invalid character in input\n");
+        exit(1);
+      }
+      result = (result << 4) | value;
+      num++;
+    }
+  }
+  
   //printf("Parsed %s as 0x%lx\n", num, result);
   return result;
 }
@@ -387,8 +421,10 @@ int main(int argc, char *argv[])
           }
           printF128("X", x); printF128("Y", y); 
           //sprintf(cmd, "0x%016lx %c 0x%016lx", x.v, op1, y.v);
+          printf("0x%016" PRIx64 "_%016" PRIx64 " %c ", x.v[1], x.v[0], op1);
+          printf("0x%016" PRIx64 "_%016" PRIx64 " ", y.v[1], y.v[0]);
           printF128(cmd, r); printFlags();
-          printF128val(r); 
+          // printF128val(r); 
         }
       }
     }