www.pudn.com > scaling.rar > scale_h2_h.h64
* ========================================================================= *
* NAME *
* scale_h2 -- Horizontal scaling by 2 *
* *
* USAGE *
* This routine has the following C prototype: *
* *
* void scale_h2_cn( *
* const unsigned char *restrict inp, *
* int cols, *
* unsigned char *restrict outp *
* ) *
* *
* *
* The scale_h2 function accepts an input array "inp" that contains *
* "cols" contiguous pixels and produces an output array "outp" of *
* "cols/2" pixels. Simple averaging and rounding are performed. *
* This step may also be viewed as simple bi-linear interpolation. *
* *
* DESCRIPTION *
* The following C code model shows the behaviour of the code. *
* *
* void scale_h2_cn( *
* const unsigned char *restrict inp, *
* int cols, *
* unsigned char *restrict outp *
* ) *
* { *
* int i; *
* *
* for( i = 0; i < (cols >> 1); i++) *
* { *
* outp[i] = (inp[2*i] + inp[(2*i)+1] + 1) >> 1; *
* } *
* } *
* *
* Every two consecutive pixels of the input image are averaged to *
* form an output pixel. *
* *
* TECHNIQUES *
* This code can be used to process either one line, or an arbitrary *
* number of lines as long as they are contiguous in memory. *
* *
* ASSUMPTIONS *
* The input array is aligned on a double-word boundary. The output *
* array is aligned on a double word boundary. The number of input *
* pixels is a multiple of 32. *
* *
* NOTES *
* None *
* *
* SOURCE *
* None *
* *
* MEMORY NOTE *
* No bank conflcits should occurr irrespective of the alignemt of *
* the arrays in memory. *
* *
* INTERRUPT NOTE *
* This code is interrupt tolerant though not interruptible. *
* *
* CYCLES *
* (5*cols)/32 - 5 *
* *
* cols = 640, cycles = 95. *
* *
* ------------------------------------------------------------------------- *
* Copyright (c) 2002 Texas Instruments, Incorporated. *
* All Rights Reserved. *
* ========================================================================= *
.global _scale_h2_asm
* ========================================================================= *
* End of file: scale_h2_h.h64 *
* ------------------------------------------------------------------------- *
* Copyright (c) 2001 Texas Instruments, Incorporated. *
* All Rights Reserved. *
* ========================================================================= *