RealView Compilation Tools - ARM Information Center

Compiler-specific Features
4.7.66 __smlad intrinsic
This intrinsic inserts an SMLAD instruction into the instruction stream generated by the
compiler. It enables you to perform two signed 16-bit multiplications, adding both
results to a 32-bit accumulate operand. The Q bit is set if the addition overflows.
Overflow cannot occur during the multiplications.
unsigned int __smlad(unsigned int val1, unsigned int val2, unsigned int val3)
Where:
val1
val2
val3
holds the first halfword operands for each multiplication
holds the second halfword operands for each multiplication
holds the accumulate value.
The __smlad intrinsic returns the product of each multiplication added to the accumulate
value, as a 32-bit integer.
Example:
unsigned int dual_multiply_accumulate(unsigned int val1, unsigned int val2,
unsigned int val3)
{
unsigned int res;
}
res = __smlad(val1,val2,val3); /* p1 = val1[15:0] × val2[15:0]
p2 = val1[31:16] × val2[31:16]
res[31:0] = p1 + p2 + val3[31:0]
*/
return res;
See also
• ARMv6 SIMD intrinsics on page 4-109
• Instruction summary on page 4-2 in the Assembler Guide
• SMLAD and SMLSD on page 4-86 in the Assembler Guide.
4-142 Copyright © 2007-2010 ARM. All rights reserved. ARM DUI 0348C
Non-Confidential,
ID101213