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![Linus Torvalds](/assets/img/avatar_default.png)
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
229 lines
5 KiB
C
229 lines
5 KiB
C
/*
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* Fast C2P (Chunky-to-Planar) Conversion
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*
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* Copyright (C) 2003 Geert Uytterhoeven
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*
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* NOTES:
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* - This code was inspired by Scout's C2P tutorial
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* - It assumes to run on a big endian system
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of this archive
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* for more details.
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*/
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#include <linux/string.h>
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#include "c2p.h"
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/*
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* Basic transpose step
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*/
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#define _transp(d, i1, i2, shift, mask) \
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do { \
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u32 t = (d[i1] ^ (d[i2] >> shift)) & mask; \
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d[i1] ^= t; \
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d[i2] ^= t << shift; \
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} while (0)
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static inline u32 get_mask(int n)
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{
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switch (n) {
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case 1:
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return 0x55555555;
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break;
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case 2:
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return 0x33333333;
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break;
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case 4:
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return 0x0f0f0f0f;
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break;
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case 8:
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return 0x00ff00ff;
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break;
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case 16:
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return 0x0000ffff;
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break;
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}
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return 0;
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}
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#define transp_nx1(d, n) \
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do { \
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u32 mask = get_mask(n); \
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/* First block */ \
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_transp(d, 0, 1, n, mask); \
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/* Second block */ \
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_transp(d, 2, 3, n, mask); \
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/* Third block */ \
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_transp(d, 4, 5, n, mask); \
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/* Fourth block */ \
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_transp(d, 6, 7, n, mask); \
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} while (0)
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#define transp_nx2(d, n) \
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do { \
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u32 mask = get_mask(n); \
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/* First block */ \
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_transp(d, 0, 2, n, mask); \
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_transp(d, 1, 3, n, mask); \
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/* Second block */ \
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_transp(d, 4, 6, n, mask); \
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_transp(d, 5, 7, n, mask); \
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} while (0)
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#define transp_nx4(d, n) \
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do { \
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u32 mask = get_mask(n); \
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_transp(d, 0, 4, n, mask); \
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_transp(d, 1, 5, n, mask); \
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_transp(d, 2, 6, n, mask); \
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_transp(d, 3, 7, n, mask); \
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} while (0)
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#define transp(d, n, m) transp_nx ## m(d, n)
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/*
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* Perform a full C2P step on 32 8-bit pixels, stored in 8 32-bit words
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* containing
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* - 32 8-bit chunky pixels on input
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* - permuted planar data on output
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*/
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static void c2p_8bpp(u32 d[8])
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{
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transp(d, 16, 4);
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transp(d, 8, 2);
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transp(d, 4, 1);
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transp(d, 2, 4);
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transp(d, 1, 2);
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}
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/*
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* Array containing the permution indices of the planar data after c2p
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*/
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static const int perm_c2p_8bpp[8] = { 7, 5, 3, 1, 6, 4, 2, 0 };
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/*
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* Compose two values, using a bitmask as decision value
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* This is equivalent to (a & mask) | (b & ~mask)
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*/
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static inline unsigned long comp(unsigned long a, unsigned long b,
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unsigned long mask)
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{
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return ((a ^ b) & mask) ^ b;
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}
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/*
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* Store a full block of planar data after c2p conversion
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*/
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static inline void store_planar(char *dst, u32 dst_inc, u32 bpp, u32 d[8])
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{
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int i;
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for (i = 0; i < bpp; i++, dst += dst_inc)
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*(u32 *)dst = d[perm_c2p_8bpp[i]];
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}
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/*
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* Store a partial block of planar data after c2p conversion
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*/
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static inline void store_planar_masked(char *dst, u32 dst_inc, u32 bpp,
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u32 d[8], u32 mask)
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{
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int i;
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for (i = 0; i < bpp; i++, dst += dst_inc)
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*(u32 *)dst = comp(d[perm_c2p_8bpp[i]], *(u32 *)dst, mask);
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}
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/*
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* c2p - Copy 8-bit chunky image data to a planar frame buffer
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* @dst: Starting address of the planar frame buffer
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* @dx: Horizontal destination offset (in pixels)
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* @dy: Vertical destination offset (in pixels)
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* @width: Image width (in pixels)
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* @height: Image height (in pixels)
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* @dst_nextline: Frame buffer offset to the next line (in bytes)
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* @dst_nextplane: Frame buffer offset to the next plane (in bytes)
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* @src_nextline: Image offset to the next line (in bytes)
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* @bpp: Bits per pixel of the planar frame buffer (1-8)
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*/
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void c2p(u8 *dst, const u8 *src, u32 dx, u32 dy, u32 width, u32 height,
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u32 dst_nextline, u32 dst_nextplane, u32 src_nextline, u32 bpp)
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{
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int dst_idx;
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u32 d[8], first, last, w;
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const u8 *c;
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u8 *p;
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dst += dy*dst_nextline+(dx & ~31);
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dst_idx = dx % 32;
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first = ~0UL >> dst_idx;
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last = ~(~0UL >> ((dst_idx+width) % 32));
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while (height--) {
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c = src;
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p = dst;
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w = width;
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if (dst_idx+width <= 32) {
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/* Single destination word */
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first &= last;
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memset(d, 0, sizeof(d));
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memcpy((u8 *)d+dst_idx, c, width);
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c += width;
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c2p_8bpp(d);
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store_planar_masked(p, dst_nextplane, bpp, d, first);
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p += 4;
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} else {
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/* Multiple destination words */
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w = width;
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/* Leading bits */
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if (dst_idx) {
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w = 32 - dst_idx;
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memset(d, 0, dst_idx);
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memcpy((u8 *)d+dst_idx, c, w);
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c += w;
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c2p_8bpp(d);
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store_planar_masked(p, dst_nextplane, bpp, d, first);
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p += 4;
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w = width-w;
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}
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/* Main chunk */
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while (w >= 32) {
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memcpy(d, c, 32);
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c += 32;
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c2p_8bpp(d);
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store_planar(p, dst_nextplane, bpp, d);
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p += 4;
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w -= 32;
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}
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/* Trailing bits */
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w %= 32;
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if (w > 0) {
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memcpy(d, c, w);
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memset((u8 *)d+w, 0, 32-w);
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c2p_8bpp(d);
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store_planar_masked(p, dst_nextplane, bpp, d, last);
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}
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}
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src += src_nextline;
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dst += dst_nextline;
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}
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}
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