91 lines
2.5 KiB
Rust
91 lines
2.5 KiB
Rust
use std::slice::from_raw_parts_mut;
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// This function is taken from
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// https://rustwasm.github.io/book/reference/code-size.html
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#[cfg(not(debug_assertions))]
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#[inline]
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pub fn unwrap_abort<T>(o: Option<T>) -> T {
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use std::process;
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match o {
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Some(t) => t,
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None => process::abort(),
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}
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}
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// Normal panic-y behavior for debug builds
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#[cfg(debug_assertions)]
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unsafe fn unchecked_unwrap<T>(o: Option<T>) -> T {
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o.unwrap()
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}
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#[no_mangle]
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fn rotate(input_width: isize, input_height: isize, rotate: isize) {
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let mut i = 0isize;
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// In the straight-copy case, d1 is x, d2 is y.
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// x starts at 0 and increases.
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// y starts at 0 and increases.
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let mut d1_start: isize = 0;
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let mut d1_limit: isize = input_width;
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let mut d1_advance: isize = 1;
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let mut d1_multiplier: isize = 1;
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let mut d2_start: isize = 0;
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let mut d2_limit: isize = input_height;
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let mut d2_advance: isize = 1;
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let mut d2_multiplier: isize = input_width;
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if rotate == 90 {
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// d1 is y, d2 is x.
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// y starts at its max value and decreases.
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// x starts at 0 and increases.
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d1_start = input_height - 1;
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d1_limit = input_height;
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d1_advance = -1;
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d1_multiplier = input_width;
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d2_start = 0;
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d2_limit = input_width;
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d2_advance = 1;
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d2_multiplier = 1;
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} else if rotate == 180 {
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// d1 is x, d2 is y.
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// x starts at its max and decreases.
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// y starts at its max and decreases.
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d1_start = input_width - 1;
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d1_limit = input_width;
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d1_advance = -1;
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d1_multiplier = 1;
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d2_start = input_height - 1;
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d2_limit = input_height;
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d2_advance = -1;
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d2_multiplier = input_width;
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} else if rotate == 270 {
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// d1 is y, d2 is x.
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// y starts at 0 and increases.
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// x starts at its max and decreases.
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d1_start = 0;
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d1_limit = input_height;
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d1_advance = 1;
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d1_multiplier = input_width;
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d2_start = input_width - 1;
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d2_limit = input_width;
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d2_advance = -1;
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d2_multiplier = 1;
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}
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let num_pixels = (input_width * input_height) as usize;
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let in_b: &mut [u32];
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let out_b: &mut [u32];
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unsafe {
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in_b = from_raw_parts_mut::<u32>(4 as *mut u32, num_pixels);
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out_b = from_raw_parts_mut::<u32>((input_width * input_height * 4 + 4) as *mut u32, num_pixels);
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}
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for d2 in 0..d2_limit {
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for d1 in 0..d1_limit {
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let in_idx = (d1_start + d1 * d1_advance) * d1_multiplier + (d2_start + d2 * d2_advance) * d2_multiplier;
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*unwrap_abort(out_b.get_mut(i as usize)) = *unwrap_abort(in_b.get(in_idx as usize));
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i += 1;
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}
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}
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}
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