| 1 |
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| 2 |
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| 3 | |
| 4 | * Copyright (c) 2024 Intel
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| 5 | * Copyright (c) 2024 Red Hat
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| 6 |
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| 7 |
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| 8 | #ifndef __DRM_PANIC_H__
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| 9 | #define __DRM_PANIC_H__
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| 10 |
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| 11 | #include <linux/module.h>
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| 12 | #include <linux/types.h>
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| 13 | #include <linux/iosys-map.h>
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| 14 |
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| 15 | #include <drm/drm_device.h>
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| 16 | #include <drm/drm_fourcc.h>
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| 17 |
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| 18 | |
| 19 | * struct drm_scanout_buffer - DRM scanout buffer
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| 20 | *
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| 21 | * This structure holds the information necessary for drm_panic to draw the
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| 22 | * panic screen, and display it.
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| 23 |
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| 24 | struct drm_scanout_buffer {
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| 25 | |
| 26 | * @format:
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| 27 | *
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| 28 | * drm format of the scanout buffer.
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| 29 |
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| 30 | const struct drm_format_info *format;
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| 31 |
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| 32 | |
| 33 | * @map:
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| 34 | *
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| 35 | * Virtual address of the scanout buffer, either in memory or iomem.
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| 36 | * The scanout buffer should be in linear format, and can be directly
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| 37 | * sent to the display hardware. Tearing is not an issue for the panic
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| 38 | * screen.
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| 39 |
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| 40 | struct iosys_map map[DRM_FORMAT_MAX_PLANES];
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| 41 |
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| 42 | |
| 43 | * @pages: Optional, if the scanout buffer is not mapped, set this field
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| 44 | * to the array of pages of the scanout buffer. The panic code will use
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| 45 | * kmap_local_page_try_from_panic() to map one page at a time to write
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| 46 | * all the pixels. This array shouldn't be allocated from the
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| 47 | * get_scanoutbuffer() callback.
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| 48 | * The scanout buffer should be in linear format.
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| 49 |
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| 50 | struct page **pages;
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| 51 |
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| 52 | |
| 53 | * @width: Width of the scanout buffer, in pixels.
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| 54 |
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| 55 | unsigned int width;
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| 56 |
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| 57 | |
| 58 | * @height: Height of the scanout buffer, in pixels.
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| 59 |
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| 60 | unsigned int height;
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| 61 |
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| 62 | |
| 63 | * @pitch: Length in bytes between the start of two consecutive lines.
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| 64 |
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| 65 | unsigned int pitch[DRM_FORMAT_MAX_PLANES];
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| 66 |
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| 67 | |
| 68 | * @set_pixel: Optional function, to set a pixel color on the
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| 69 | * framebuffer. It allows to handle special tiling format inside the
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| 70 | * driver. It takes precedence over the @map and @pages fields.
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| 71 |
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| 72 | void (*set_pixel)(struct drm_scanout_buffer *sb, unsigned int x,
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| 73 | unsigned int y, u32 color);
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| 74 |
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| 75 | |
| 76 | * @private: private pointer that you can use in the callbacks
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| 77 | * set_pixel()
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| 78 |
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| 79 | void *private;
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| 80 |
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| 81 | };
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| 82 |
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| 83 | #ifdef CONFIG_DRM_PANIC
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| 84 |
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| 85 | |
| 86 | * drm_panic_trylock - try to enter the panic printing critical section
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| 87 | * @dev: struct drm_device
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| 88 | * @flags: unsigned long irq flags you need to pass to the unlock() counterpart
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| 89 | *
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| 90 | * This function must be called by any panic printing code. The panic printing
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| 91 | * attempt must be aborted if the trylock fails.
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| 92 | *
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| 93 | * Panic printing code can make the following assumptions while holding the
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| 94 | * panic lock:
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| 95 | *
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| 96 | * - Anything protected by drm_panic_lock() and drm_panic_unlock() pairs is safe
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| 97 | * to access.
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| 98 | *
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| 99 | * - Furthermore the panic printing code only registers in drm_dev_unregister()
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| 100 | * and gets removed in drm_dev_unregister(). This allows the panic code to
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| 101 | * safely access any state which is invariant in between these two function
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| 102 | * calls, like the list of planes &drm_mode_config.plane_list or most of the
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| 103 | * struct drm_plane structure.
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| 104 | *
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| 105 | * Specifically thanks to the protection around plane updates in
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| 106 | * drm_atomic_helper_swap_state() the following additional guarantees hold:
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| 107 | *
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| 108 | * - It is safe to deference the drm_plane.state pointer.
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| 109 | *
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| 110 | * - Anything in struct drm_plane_state or the driver's subclass thereof which
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| 111 | * stays invariant after the atomic check code has finished is safe to access.
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| 112 | * Specifically this includes the reference counted pointers to framebuffer
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| 113 | * and buffer objects.
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| 114 | *
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| 115 | * - Anything set up by &drm_plane_helper_funcs.fb_prepare and cleaned up
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| 116 | * &drm_plane_helper_funcs.fb_cleanup is safe to access, as long as it stays
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| 117 | * invariant between these two calls. This also means that for drivers using
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| 118 | * dynamic buffer management the framebuffer is pinned, and therefer all
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| 119 | * relevant datastructures can be accessed without taking any further locks
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| 120 | * (which would be impossible in panic context anyway).
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| 121 | *
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| 122 | * - Importantly, software and hardware state set up by
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| 123 | * &drm_plane_helper_funcs.begin_fb_access and
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| 124 | * &drm_plane_helper_funcs.end_fb_access is not safe to access.
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| 125 | *
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| 126 | * Drivers must not make any assumptions about the actual state of the hardware,
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| 127 | * unless they explicitly protected these hardware access with drm_panic_lock()
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| 128 | * and drm_panic_unlock().
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| 129 | *
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| 130 | * Return:
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| 131 | * %0 when failing to acquire the raw spinlock, nonzero on success.
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| 132 |
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| 133 | #define drm_panic_trylock(dev, flags) \
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| 134 | raw_spin_trylock_irqsave(&(dev)->mode_config.panic_lock, flags)
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| 135 |
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| 136 | |
| 137 | * drm_panic_lock - protect panic printing relevant state
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| 138 | * @dev: struct drm_device
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| 139 | * @flags: unsigned long irq flags you need to pass to the unlock() counterpart
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| 140 | *
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| 141 | * This function must be called to protect software and hardware state that the
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| 142 | * panic printing code must be able to rely on. The protected sections must be
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| 143 | * as small as possible. It uses the irqsave/irqrestore variant, and can be
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| 144 | * called from irq handler. Examples include:
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| 145 | *
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| 146 | * - Access to peek/poke or other similar registers, if that is the way the
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| 147 | * driver prints the pixels into the scanout buffer at panic time.
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| 148 | *
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| 149 | * - Updates to pointers like &drm_plane.state, allowing the panic handler to
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| 150 | * safely deference these. This is done in drm_atomic_helper_swap_state().
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| 151 | *
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| 152 | * - An state that isn't invariant and that the driver must be able to access
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| 153 | * during panic printing.
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| 154 |
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| 155 |
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| 156 | #define drm_panic_lock(dev, flags) \
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| 157 | raw_spin_lock_irqsave(&(dev)->mode_config.panic_lock, flags)
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| 158 |
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| 159 | |
| 160 | * drm_panic_unlock - end of the panic printing critical section
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| 161 | * @dev: struct drm_device
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| 162 | * @flags: irq flags that were returned when acquiring the lock
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| 163 | *
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| 164 | * Unlocks the raw spinlock acquired by either drm_panic_lock() or
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| 165 | * drm_panic_trylock().
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| 166 |
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| 167 | #define drm_panic_unlock(dev, flags) \
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| 168 | raw_spin_unlock_irqrestore(&(dev)->mode_config.panic_lock, flags)
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| 169 |
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| 170 | #else
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| 171 |
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| 172 | static inline bool drm_panic_trylock(struct drm_device *dev, unsigned long flags)
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| 173 | {
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| 174 | return true;
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| 175 | }
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| 176 |
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| 177 | static inline void drm_panic_lock(struct drm_device *dev, unsigned long flags) {}
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| 178 | static inline void drm_panic_unlock(struct drm_device *dev, unsigned long flags) {}
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| 179 |
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| 180 | #endif
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| 181 |
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| 182 | #if defined(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
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| 183 | size_t drm_panic_qr_max_data_size(u8 version, size_t url_len);
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| 184 |
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| 185 | u8 drm_panic_qr_generate(const char *url, u8 *data, size_t data_len, size_t data_size,
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| 186 | u8 *tmp, size_t tmp_size);
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| 187 | #endif
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| 188 |
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| 189 | #endif
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