Patent ID: 6289386
Filing Date: 2001-09-11
Classification: H04L

Abstract:
A serial communication adapter which comprises:a receive buffer for storing received data frames having a maximum frame size, wherein the receive buffer has a predetermined storage capacity;a receive controller coupled to the receive buffer, wherein the receive controller is configured to track the amount of available buffer space in the receive buffer by maintaining an available buffer space value, wherein the available buffer space value is increased by an amount corresponding to less than the maximum frame size in response to receiving frames having a size less than the maximum frame size;a transmit controller configured to send a buffer credit in response to a credit signal, wherein the buffer credit is indicative of available space for a data frame in the receive buffer;a buffer credit manager coupled to the receive controller to receive a receive flag for each received complete data frame and coupled to the transmit controller to receive a transmit flag for each buffer credit sent, wherein the buffer credit manager maintains a committed space value corresponding to additional committed buffer space, wherein the committed space value is incremented by an amount corresponding to the maximum frame size in response to the transmit controller sending a buffer credit and is decremented by the amount corresponding to the maximum frame size in response to the receiver buffer receiving a data frame, wherein the buffer credit manager includes a comparator configured to compare the committed space value to the available buffer space value and is configured to assert the credit signal in response to determining that the available buffer space is greater than the additional committed buffer space by at least the maximum frame size.