Implementation of various scalers with following properties:
- written in pure assembler
- uses ARMv7 and NEON instructions
- uses instruction scheduling for Cortex-A8 processors
- no checking for corectness of parameters
- no clipping
- MIT license
The scaler function definitions are in the header files in the include directory.
Compiled libaries (static and shared) are in the lib directory.
##Description of scaler function names neon_NAME_SP_DP
where NAME is the scaler name,
SP is the number of bits per source pixel,
DP is the number of bits per destination pixel
list of values:
NAME: normal1x, normal2x, normal3x, normal4x, scale2x, scale3x, scale4x, eagle2x
SP->DP: 8->8, 8->16, 16->16
##Description of scaler function parameters
src
pointer to the first source pixel
if bits per source pixel is 16 then src must be aligned to 16 bits (2 bytes)
dst
pointer to the first destination pixel
if bits per destination pixel is 16 then dst must be aligned to 16 bits (2 bytes)
palette
pointer to an array of 256 32-bit values
upper 16 bits of every value must be zero
must be aligned to 32 bits (4 bytes)
width
width of the source image (in pixels)
minimum width is 32
srcstride
stride of the source image (in bytes) = distance between two lines in the source image
dststride
stride of the destination image (in bytes) = distance between two lines in the destination image
height
height of the source image
minimum height is 3
##Example Scaling 320x200 image (16-bits per pixel) using scale2x to the center of a 800x480 frame
uint16_t src[320*200];
uint16_t dst[800x480];
neon_scale2x_16_16(&(src[0]), &(dst[((480 - 2*200) / 2) * 800 + (800 - 320 * 2) / 2]), 320, 320*2, 800*2, 200);