Total revenue for 2022 was $134.6 million, an increase of 10%, when compared to $122.7 million reported for 2021. Licensing, NRE and related revenue for 2022 was a record $89.3 million, an increase of 23% when compared to $72.8 million reported for 2021. Royalty revenue for 2022 was $45.4 million, representing a decrease of 9%, as compared to $49.9 million reported for 2021.
GAAP gross margin for 2022 was 80%, as compared to GAAP gross margin of 86% for the same period in 2021. GAAP operating loss for 2022 was $5.4 million, as compared to a GAAP operating income of $3.5 million reported for 2021. GAAP net loss and diluted loss per share for 2022 were $23.2 million and $1.00, respectively, compared to GAAP net income and diluted earnings per share of $0.4 million and $0.02, respectively, reported for 2021.
Non-GAAP gross margin for 2022 was 84%, as compared to non-GAAP gross margin of 88% for the same period in 2021. Non-GAAP operating income for 2022 was $22.3, compared with $22.7 million reported for 2021. Non-GAAP net income and diluted earnings per share for 2022 were $18.8 million and $0.78, respectively, representing an increase of 23% and 20%, respectively, over $15.3 million and $0.65 reported for 2021.
This earnings release discusses non-GAAP gross margin, non-GAAP operating income (loss), non-GAAP net income (loss) and non-GAAP earnings (loss) per share, which are not financial measures as defined by GAAP. These financial measures are presented as supplemental measures of operating performance because the exclusion of certain expenses discussed below may provide a more meaningful analysis of our core operating results and comparison of quarterly results. Further, we believe it is useful for investors to understand how the expenses associated with the application of FASB ASC No. 718 are reflected on our statements of income. The reconciliation of financial measures should be reviewed in addition to and in conjunction with results presented in accordance with GAAP, and are intended to provide additional insight into our operations that, when viewed with its GAAP results and the accompanying reconciliation, offer a more complete understanding of factors and trends affecting our business. Other companies may define or calculate these measures differently, limiting the usefulness as a comparative measure. Because of these limitations, these non-GAAP financial measures should not be considered in isolation or as substitute for or superior to performance measures calculated in accordance with GAAP and should be read in conjunction with the financial statement tables.
Non-GAAP gross margin for the fourth quarter of 2022 excluded: (a) equity-based compensation expenses of $0.4 million and, (b) amortization of acquired intangibles of $0.4 million. Non-GAAP gross margin for the fourth quarter of 2021 excluded: (a) additional NRE revenues associated with the purchase price allocation (PPA) related to Intrinsix acquisition of $0.2 million, (b) equity-based compensation expenses of $0.3 million and (c) amortization of acquired intangibles of $1.0 million.
Non-GAAP operating income for the fourth quarter of 2022 excluded: (a) equity-based compensation expenses of $4.1 million, (b) the impact of the amortization of acquired intangibles of $0.9 million associated with the acquisition of the Intrinsix and Hillcrest Labs businesses and investments in NB-IoT and Immervision technologies, (c) $0.3 million of costs associated with the Intrinsix acquisition, (d) impairment cost of $0.3 million associated with the closing of an office and (e) $1.3 million associated with retirement expenses of executives. Non-GAAP operating income for the fourth quarter of 2021 excluded: (a) equity-based compensation expenses of $3.5 million, (b) the impact of the amortization of acquired intangibles of $1.6 million associated with the acquisition of the Intrinsix and Hillcrest Labs business and investments in NB-IoT and Immervision technologies, (c) $0.3 million of costs associated with the Intrinsix acquisition and (d) an addition of $0.2 million in licensing, NRE and related revenues associated with purchase price allocation for the Intrinsix acquisition.
Non-GAAP net income and diluted earnings per share for the fourth quarter of 2022 excluded: (a) equity-based compensation expenses of $4.1 million, (b) the impact of the amortization of acquired intangibles of $0.9 million associated with the acquisition of the Intrinsix and Hillcrest Labs businesses and investments in NB-IoT technologies, (c) $0.3 million of costs associated with the Intrinsix acquisition, (d) $0.2 million associated with the reevaluation of an investment in another company, (e) impairment cost of $0.3 million associated with close of an office, (f) $1.3 million associated with retirement expenses of executives and (g) $3.5 million adjustment as a result of implementing the US tax reform rule 174. Non-GAAP net income and diluted earnings per share for the fourth quarter of 2021 excluded: (a) equity-based compensation expenses, net of taxes, of $2.7 million, (b) the impact of the amortization of acquired intangibles, net of taxes, of $1.4 million associated with the acquisition of the Intrinsix and Hillcrest Labs businesses and investments in NB-IoT and Immervision technologies, (c) $0.3 million of costs associated with the Intrinsix acquisition, (d) $1.5 million of income, net of taxes associated with the reevaluation of an investment in another company, (e) $1.7 million of income tax benefit associated with the purchase price allocation related to the Intrinsix acquisition and (f) an addition of $0.2 million in licensing, NRE and related revenues associated with purchase price allocation for the Intrinsix acquisition.
Non-GAAP gross margin for 2022 excluded: (a) equity-based compensation expenses of $1.5 million and, (b) amortization and impairment of acquired intangibles of $3.9 million. Non-GAAP gross margin for 2021 excluded: (a) additional NRE revenues associated with the purchase price allocation (PPA) related to Intrinsix acquisition of $0.2 million, (b) equity-based compensation expenses of $0.8 million and (c) amortization of acquired intangibles of $1.6 million.
Non-GAAP operating income for 2022 excluded: (a) equity-based compensation expenses of $14.5 million, (b) the impact of the amortization of acquired intangibles of $4.7 million associated with the acquisition of the Intrinsix and Hillcrest Labs businesses and investments in NB-IoT and Immervision technologies, (c) $1.3 million of costs associated with the Intrinsix acquisition, (d) impairment charges of $5.5 million relating to discontinued Immervision technology and non-performing assets of certain NB-IoT technology, $3.5 million of which was recorded in operating expenses and $2.0 million of which was recorded in cost of revenues, (e) impairment cost of 0.3 million associated with close of an office and (f) an addition of $1.3 million associated with retirement expenses of executives. Non-GAAP operating income for 2021 excluded: (a) equity-based compensation expenses of $13.1 million, (b) the impact of the amortization of acquired intangibles of $4.3 million associated with the acquisition of the Intrinsix and Hillcrest Labs businesses and investments in NB-IoT and Immervision technologies, (c) $1.7 million of costs associated with the Intrinsix acquisition and (d) an addition of $0.2 million in licensing, NRE and related revenues associated with purchase price allocation for the Intrinsix acquisition.
Non-GAAP net income and diluted earnings per share for 2022 excluded: (a) equity-based compensation expenses of $14.5 million, (b) the impact of the amortization of acquired intangibles of $4.7 million associated with the acquisition of the Intrinsix and Hillcrest Labs businesses and investments in NB-IoT and Immervision technologies, (c) $1.3 million of costs associated with the Intrinsix acquisition, (d) $2.0 million , net of taxes, associated with the reevaluation of an investment in another company, (e) impairment charges of $5.5 million relating to discontinued Immervision technology and non-performing assets of certain NB-IoT technology, $3.5 million of which was recorded in operating expenses and $2.0 million of which was recorded in cost of revenues, (f) $15.8 million write-off of a deferred tax asset, including withholding tax assets that we will not be able to utilize as a tax credit, which was recorded in the income tax expense line item, (g) impairment cost of $0.3 million associated with the closure of an office, (h) $1.3 million associated with retirement expenses of executives and (i) $3.5 million adjustment as a result of implementing the US tax reform rule 174. Non-GAAP net income and diluted earnings per share for 2021 excluded: (a) equity-based compensation expenses, net of taxes, of $12.2 million , (b) the impact of the amortization of acquired intangibles, net of taxes, of $4.0 million associated with the acquisition of the Intrinsix and Hillcrest Labs businesses and investments in NB-IoT and Immervision technologies, (c) $1.7 million of costs associated with the Intrinsix acquisition, (d) $1.5 million of income, net of taxes, associated with the reevaluation of an investment in another company, (e) $1.7 million of income tax benefit associated with the purchase price allocation related to the Intrinsix acquisition and (f) an addition of $0.2 million in licensing, NRE and related revenues associated with purchase price allocation for the Intrinsix acquisition.
