Method and apparatus for avoiding non-aligned loads using multiple copies of input data

A method of determining a summation of pixel characteristics for a rectangular region of a digital image, comprising:

• determining if first, second, third, and fourth base addresses for respective first, second, third, and fourth data elements in an integral image buffer are aligned for respective first, second, third, and fourth single instruction multiple data (SIMD) operations by a processor embedded in an electronic assembly configured to perform Haar-like feature calculations, wherein the first, second, third, and fourth data elements respectively represent upper left, upper right, lower left, and lower right corners of a pre-selected rectangular region of an integral image, wherein the integral image is a representation of a pre-selected digital image, wherein the integral image is formed by data elements stored in the integral image buffer on a storage device accessible to the processor;
• loading the first, second, third, and fourth data elements from the integral image buffer to the processor when the respective first, second, third, and fourth base address is aligned for the respective first, second, third, and fourth SIMD operation;
• and
• loading offset first, offset second, offset third, and offset fourth data elements of an offset integral image from an offset integral buffer on the storage device to the processor when the respective first, second, third, and fourth base address is non-aligned for the respective first, second, third, and fourth SIMD operation, wherein the offset first, offset second, offset third, and offset fourth data elements respectively represent the upper left, upper right, lower left, and lower right corners of the pre-selected rectangular region;
• wherein the offset data elements of the offset integral image are defined by the corresponding data elements of the integral image and stored at address locations in the offset integral buffer that are offset right or left by one address location such that a select data element in the integral image buffer at a select address that is non-aligned for a select SIMD operation by the processor is located at a select offset address in the offset integral buffer that is aligned for the select SIMD operation.

A non-transitory computer-readable medium storing program instructions that, when executed by a processor embedded in a processor-controlled electronic assembly configured to perform Haar-like feature calculations, cause the processor-controlled electronic assembly to perform a method of deteimining a summation of pixel characteristics for a rectangular region of a digital image, the method comprising:

• determining if first, second, third, and fourth base addresses for respective first, second, third, and fourth data elements in an integral image buffer are aligned for respective first, second, third, and fourth single instruction multiple data (SIMD) operations by a processor embedded in an electronic assembly configured to perform Haar-like feature calculations, wherein the first, second, third, and fourth data elements respectively represent upper left, upper right, lower left, and lower right corners of a pre-selected rectangular region of an integral image, wherein the integral image is a representation of a pre-selected digital image, wherein the integral image is formed by data elements stored in the integral image buffer on a storage device accessible to the processor;
• loading the first, second, third, and fourth data elements from the integral image buffer to the processor when the respective first, second, third, and fourth base address is aligned for the respective first, second, third, and fourth SIMD operation;
• and
• loading offset first, offset second, offset third, and offset fourth data elements of an offset integral image from an offset integral buffer on the storage device to the processor when the respective first, second, third, and fourth base address is non-aligned for the respective first, second, third, and fourth SIMD operation, wherein the offset first, offset second, offset third, and offset fourth data elements respectively represent the upper left, upper right, lower left, and lower right corners of the pre-selected rectangular region;
• wherein the offset data elements of the offset integral image are defined by the corresponding data elements of the integral image and stored at address locations in the offset integral buffer that are offset right or left by one address location such that a select data element in the integral image buffer at a select address that is non-aligned for a select SIMD operation by the processor is located at a select offset address in the offset integral buffer that is aligned for the select SIMD operation, the method further comprising:
• calculating a summation of pixel characteristics for the pre-selected rectangular region using a regional area algorithm accessible to the processor by subtracting the corresponding data elements for the upper right corner and the lower left corner from a sum of the corresponding data elements for the upper left corner and the lower right corner.