28.2.47 __builtin_ff1l_32

Architecture

dsPIC33A

Description:

Finds the first one-bit from the left. The most left bit is numbered bit 1, increasing towards the least significant bit.

Example:

int result;
int32_t val_1 = 2048;
int32_t val_2 = -2048;
 
result = __builtin_ff1l_32(val_1);
result = __builtin_ff1l_32(val_2);

The first one-bit for 2048 == 0x0000.0800 == 0b0000.0000.0000.0000.0000.1000.0000.0000 is 21.  The first one-bit  for -2048 == 0xFFFF.F800 == 0b1111.1111.1111.1111.1111.1000.0000.0000 is 1.

Prototype

int __builtin_ff1l_32(int32_t x);

Arguments

x  - value to inspect

Return Value

Returns the position of the first one-bit from the left (most-significant bit).  The value is sign-extended to an int.

Machine Instruction

ff1l.l

Error Messages

None.