Developer Guide and Reference

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_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))
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