neon_scalers

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Scalers using ARMV7, NEON instructions with instruction scheduling for Cortex-A8 processors

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# neon_scalers

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

```c_cpp
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);
```

neon_scalers

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