04.01.2015 Views

RealView Compilation Tools - ARM Information Center

RealView Compilation Tools - ARM Information Center

RealView Compilation Tools - ARM Information Center

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Compiler-specific Features<br />

4.7.98 __uqsub8 intrinsic<br />

This intrinsic inserts a UQSUB8 instruction into the instruction stream generated by the<br />

compiler. It enables you to perform four unsigned 8-bit integer subtractions, saturating<br />

the results to the 8-bit unsigned integer range 0 ≤ x ≤ 2 8 - 1.<br />

unsigned int __uqsub8(unsigned int val1, unsigned int val2)<br />

Where:<br />

val1<br />

val2<br />

holds the first four 8-bit operands<br />

holds the second four 8-bit operands.<br />

The __uqsub8 intrinsic returns:<br />

• the subtraction of the first byte in the second operand from the first byte in the first<br />

operand, in the first byte of the return value<br />

• the subtraction of the second byte in the second operand from the second byte in<br />

the first operand, in the second byte of the return value<br />

• the subtraction of the third byte in the second operand from the third byte in the<br />

first operand, in the third byte of the return value<br />

• the subtraction of the fourth byte in the second operand from the fourth byte in<br />

the first operand, in the fourth byte of the return value.<br />

The results are saturated to the 8-bit unsigned integer range 0 ≤ x ≤ 2 8 - 1.<br />

Example:<br />

unsigned int subtract_bytes(unsigned int val1, unsigned int val2)<br />

{<br />

unsigned int res;<br />

}<br />

res = __uqsub8(val1,val2); /* res[7:0] = val1[7:0] - val2[7:0]<br />

res[15:8] = val1[15:8] - val2[15:8]<br />

res[23:16] = val1[23:16] - val2[23:16]<br />

res[31:24] = val1[31:24] - val2[31:24]<br />

*/<br />

return res;<br />

See also<br />

• <strong>ARM</strong>v6 SIMD intrinsics on page 4-109<br />

• Instruction summary on page 4-2 in the Assembler Guide<br />

• Parallel add and subtract on page 4-99 in the Assembler Guide.<br />

4-176 Copyright © 2007-2010 <strong>ARM</strong>. All rights reserved. <strong>ARM</strong> DUI 0348C<br />

Non-Confidential,<br />

ID101213

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!