12.58 __usub16 intrinsic
This intrinsic inserts a
USUB16 instruction into the instruction stream generated by the compiler.
you to perform two 16-bit unsigned integer subtractions.
The GE bits in the APSR are set according to the results.
unsigned int __usub16(unsigned int
, unsigned int
holds the first two halfword operands
holds the second two halfword operands.
__usub16 intrinsic returns:
The subtraction of the low halfword in the second
operand from the low halfword in the first operand, in the low halfword
of the return value.
The subtraction of the high halfword in the second
operand from the high halfword in the first operand, in the high
halfword of the return value.
Each bit in APSR.GE is set or cleared for each byte in the
return value, depending on the results of the operation. If
the return value, then:
unsigned int subtract_halfwords(unsigned int val1, unsigned int val2)
unsigned int res;
res = __usub16(val1,val2); /* res[15:0] = val1[15:0] - val2[15:0]
res[31:16] = val1[31:16] - val2[31:16]