A yarn feeder is provided with a drum which is driven to rotate by a motor controlled by a control unit for drawing yarn from a reel and winding it upon itself in the shape of loops forming a stock. The control unit estimates the stock on the drum on the basis of an information indicative of the amount of yarn which is unwound from the drum upon request from a downstream machine, and of an information indicative of the amount of yarn which is wound on the drum, and retroactively controls the motor to substantially stabilize the stock on a reference value. The control unit also performs a parallel correction routine in which compares the stock with the reference value to estimate a stock status RES<REF_RES or RESREF_RES, wherein RES is the estimated stock and REF_RES is the reference value.

A device for feeding yarn to a textile machine, including a main body defining an entry portion and an exit portion for yarn; a rotatable drum for winding the yarn originating from the entry portion and a motor connected to the drum for rotating the drum; a control member active at least on the motor to regulate its torque and velocity; exit portion being selectively switchable between a first configuration in which it defines a free exit section for the yarn, through which the exiting yarn defines a closed path about a rotation axis of the drum, and a second configuration in which it defines a limited exit section, through which the exiting yarn defines an open path.