Changeset cefb126 in mainline for uspace/lib/softint/generic/multiplication.c

Timestamp:

2010-07-02T14:19:30Z (14 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

89c57b6

Parents:

fe7abd0 (diff), e3ee9b9 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge mainline changes.

File:

• uspace/lib/softint/generic/multiplication.c (modified) (3 diffs)

uspace/lib/softint/generic/multiplication.c

@@ -29 +29 @@
 /** @addtogroup softint
  * @{
- */ 
+ */
 /**
  * @file
@@ -36 +36 @@
 
 #include <multiplication.h>
-#include <stdint.h> 
+#include <stdint.h>
 
-/** Set 1 to return MAX_INT64 or MIN_INT64 on overflow */
+/** Set 1 to return INT64_MAX or INT64_MIN on overflow */
 #ifndef SOFTINT_CHECK_OF
-# define SOFTINT_CHECK_OF 0
+        #define SOFTINT_CHECK_OF  0
 #endif
 
-/**
- * Multiply two integers and return long long as result. 
+/** Multiply two integers and return long long as result.
+ *
  * This function is overflow safe.
- * @param a
- * @param b
- * @result
+ *
  */
 static unsigned long long mul(unsigned int a, unsigned int b) {
-        unsigned int a1, a2, b1, b2;
-        unsigned long long t1, t2, t3;  
-
-        a1 = a >> 16;
-        a2 = a & MAX_UINT16;
-        b1 = b >> 16;
-        b2 = b & MAX_UINT16;
-
-        t1 = a1 * b1;
-        t2 = a1*b2;
-        t2 += a2*b1;
-        t3 = a2*b2;
-
-        t3 = (((t1 << 16) + t2) << 16) + t3; 
-
+        unsigned int a1 = a >> 16;
+        unsigned int a2 = a & UINT16_MAX;
+        unsigned int b1 = b >> 16;
+        unsigned int b2 = b & UINT16_MAX;
+        
+        unsigned long long t1 = a1 * b1;
+        unsigned long long t2 = a1 * b2;
+        t2 += a2 * b1;
+        unsigned long long t3 = a2 * b2;
+        
+        t3 = (((t1 << 16) + t2) << 16) + t3;
+        
         return t3;
 }
@@ -74 +69 @@
 long long __muldi3 (long long a, long long b)
 {
-        long long result;
-        unsigned long long t1,t2;
-        unsigned long long a1, a2, b1, b2;
         char neg = 0;
-
+        
         if (a < 0) {
                 neg = !neg;
                 a = -a;
         }
-
+        
         if (b < 0) {
                 neg = !neg;
                 b = -b;
         }
-
-        a1 = a >> 32;
-        b1 = b >> 32;
-
-        a2 = a & (MAX_UINT32);
-        b2 = b & (MAX_UINT32);
-
+        
+        unsigned long long a1 = a >> 32;
+        unsigned long long b1 = b >> 32;
+        
+        unsigned long long a2 = a & (UINT32_MAX);
+        unsigned long long b2 = b & (UINT32_MAX);
+        
         if (SOFTINT_CHECK_OF && (a1 != 0) && (b1 != 0)) {
-                // error, overflow
-                return (neg?MIN_INT64:MAX_INT64);
+                /* Error (overflow) */
+                return (neg ? INT64_MIN : INT64_MAX);
         }
-
-        // (if OF checked) a1 or b1 is zero => result fits in 64 bits, no need to another overflow check
-        t1 = mul(a1,b2) + mul(b1,a2);   
-
-        if (SOFTINT_CHECK_OF && t1 > MAX_UINT32) {
-                // error, overflow
-                return (neg?MIN_INT64:MAX_INT64);
+        
+        /* (if OF checked) a1 or b1 is zero => result fits in 64 bits,
+         * no need to another overflow check
+         */
+        unsigned long long t1 = mul(a1, b2) + mul(b1, a2);
+        
+        if ((SOFTINT_CHECK_OF) && (t1 > UINT32_MAX)) {
+                /* Error (overflow) */
+                return (neg ? INT64_MIN : INT64_MAX);
         }
-
+        
         t1 = t1 << 32;
-        t2 = mul(a2,b2);
+        unsigned long long t2 = mul(a2, b2);
         t2 += t1;
-
+        
         /* t2 & (1ull << 63) - if this bit is set in unsigned long long,
          * result does not fit in signed one */
         if (SOFTINT_CHECK_OF && ((t2 < t1) || (t2 & (1ull << 63)))) {
                 // error, overflow
-                return (neg?MIN_INT64:MAX_INT64);
+                return (neg ? INT64_MIN : INT64_MAX);
         }
-
-        result = t2;
-
-        if (neg) {
+        
+        long long result = t2;
+        if (neg)
                 result = -result;
-        }
-
+        
         return result;
-}       
+}
 
 /** @}