# _subborrow_u32(), _subborrow_u64()

Computes sum of 32/64 bit unsigned integer value with borrow-in value and then subtracts the result from a 32/64 bit unsigned integer value. The corresponding 4th Generation Intel® Core™ Processor extension instruction is `V`.

## Syntax

extern unsigned char _subborrow_u32(unsigned char b_in, unsigned int src1, unsigned int src2, unsigned int *diff_out);

extern unsigned char _subborrow_u64(unsigned char b_in, unsigned __int64 src1, unsigned __int64 src2, unsigned __int64 *diff_out);

## Parameters

b_in | Borrow-in value for addition operation
src1 | 32/64 bit source integer for addition operation
src2 | 32/64 bit source integer for subtraction operation
*diff_out | Pointer to memory location where result is stored

## Description

Computes the sum of a 32/64 bit wide unsigned integer value src2 and a borrow-in value b_in and then subtracts result of the sum from 32/64 bit wide unsigned integer value src1. The borrow-in value is considered '1' for any non-zero b_in input value, or '0' otherwise. The difference is then stored to a memory location referenced by diff_out argument:

     *diff_out = src1 - (src2 + (b_in !=0 ? 1 : 0))

### Note

This intrinsic does not perform validity checking of the memory address pointed to by diff_out, thus it cannot be used to find out if a subtraction produces borrow-out without storing the result of the subtraction.

## Returns

Returns borrow-out value generated by subtraction operation. The result of the subtraction is stored into memory location pointed by diff_out argument.

Parent topic: Intrinsics for Multi-Precision Arithmetic