| # Chebyshev evaluation with interval rescaled to [0,1] | |
| xp = 2*x - 1 # remap to [-1,1] that Cheb basis is easier in | |
| # Constant and linear terms | |
| result = coeffs[0] + xp*coeffs[1] | |
| # Recurrence for remaining terms | |
| cur, prev = xp, 1 | |
| t = xp * 2 |
| #!/bin/sh | |
| r2 -qc "e anal.bb.maxsize=2048;s sym.$2;af;agfj" "$1" | python3 control-flow-graph.py |
| // KI25 -- Keep It 2hort 5tupid | |
| // TABA -- These Are Bad Acronyms | |
| // - (probably) bad variable names | |
| // - horrible function names | |
| // - reserve for extremely common stuff | |
| #define si static inline | |
| #include <stdint.h> |
| #include "ki25.h" | |
| // convert an index into a coordinate, | |
| // given a width `w` and height `h` | |
| si u16 xcoord(u32 i, u16 w, u16 h) { return i % w; } | |
| si u16 ycoord(u32 i, u16 w, u16 h) { return i / w; } | |
| // normalize value on a scale from `0` to `s` | |
| si f32 fnorm(u16 x, u16 s) { return (f32)x / s; } |
let w and h be the width and the height of the screen, respectively.
let a be the ratio of the width to the height.
a = w / h
Note that this is equivalent to the aspect ratio of the screen for the case where the screen is wider than it is tall, and the inverse of the aspect ratio otherwise.
Let q be the area of the screen.
| [jamin@dependent 2018-06-06-bindump]$ perf stat -e task-clock,cycles,instructions,cache-references,cache-misses | |
| ./say hello > /dev/null | |
| Performance counter stats for './say hello': | |
| 0.197061 task-clock:u (msec) # 0.363 CPUs utilized | |
| 133682 cycles:u # 0.678 GHz | |
| 115712 instructions:u # 0.87 insn per cycle | |
| 1486 cache-references:u # 7.541 M/sec | |
| 937 cache-misses:u # 63.055 % of all cache refs |
| #!/usr/bin/python3 | |
| # Per's code | |
| def sw_binary_divide2(n, d, num_bits): | |
| q = 0 | |
| r = n | |
| d2 = d << (num_bits - 1) | |
| for i in range(num_bits): | |
| q <<= 1 | |
| if r >= d2: |
| // Retro Arch has a bunch of options and fiddly bits | |
| // this is a starting point with just enough wired up to hack on some demos | |
| // build with `gcc -shared -fPIC -o retroarch-scratch.so retroarch-scratch.c` | |
| // run with `retroarch -L retroarch-scratch.so` | |
| // docs are good | |
| // https://github.com/libretro/libretro.github.com/blob/master/documents/libretro.pdf | |
| // https://github.com/libretro/RetroArch/blob/master/libretro-common/include/libretro.h |
| 21:27:39.987070 IP 127.0.0.1.1234 > 224.0.0.1.1234: UDP, length 60 | |
| 0x0000: 4500 0058 4699 4000 0111 d3f9 7f00 0001 | |
| 0x0010: e000 0001 04d2 04d2 0044 5f58 ffff ffff | |
| 0x0020: ffff 5254 0012 3457 0806 0001 0800 0604 | |
| 0x0030: 0001 5254 0012 3457 0a00 0802 0000 0000 | |
| 0x0040: 0000 0a00 0803 0000 0000 0000 0000 0000 | |
| 0x0050: 0000 0000 0000 0000 |
| This just got linked to by the Y combinator news account, without proper context, | |
| so a brief introduction: A month ago (end of May / early June 2014) I had a | |
| Twitter conversation with a bunch of acquaintances. One tweet in the middle | |
| of that thread, with obligatory hyperbole, was me saying that I think VR is | |
| bad news. | |
| Well, that part of the thread (but not the rest that provides context) recently | |
| got retweeted, and then someone asked me if I could explain what I mean by that, | |
| and because Twitter is a great platform for delivering 140 character slogans and | |
| not so great for lengthy explanations, I wrote this. So, obligatory disclaimer: |