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cosmopolitan/libc/nexgen32e/bsr.h

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Initial import
2020-06-15 14:18:57 +00:00
#ifndef COSMOPOLITAN_LIBC_NEXGEN32E_BSR_H_
#define COSMOPOLITAN_LIBC_NEXGEN32E_BSR_H_
#if !(__ASSEMBLER__ + __LINKER__ + 0)
COSMOPOLITAN_C_START_
Add x86_64-linux-gnu emulator I wanted a tiny scriptable meltdown proof way to run userspace programs and visualize how program execution impacts memory. It helps to explain how things like Actually Portable Executable works. It can show you how the GCC generated code is going about manipulating matrices and more. I didn't feel fully comfortable with Qemu and Bochs because I'm not smart enough to understand them. I wanted something like gVisor but with much stronger levels of assurances. I wanted a single binary that'll run, on all major operating systems with an embedded GPL barrier ZIP filesystem that is tiny enough to transpile to JavaScript and run in browsers too. https://justine.storage.googleapis.com/emulator625.mp4
2020-08-25 11:23:25 +00:00
/*
* BIT SCANNING 101
* ctz(𝑥) 31^clz(𝑥) clz(𝑥)
* uint32 𝑥 bsf(𝑥) tzcnt(𝑥) ffs(𝑥) bsr(𝑥) lzcnt(𝑥)
* 0x00000000 wut 32 0 wut 32
* 0x00000001 0 0 1 0 31
* 0x80000001 0 0 1 31 0
* 0x80000000 31 31 32 31 0
* 0x00000010 4 4 5 4 27
* 0x08000010 4 4 5 27 4
* 0x08000000 27 27 28 27 4
* 0xffffffff 0 0 1 31 0
*/
Initial import
2020-06-15 14:18:57 +00:00
Add pseudoteletypewriter to emulator https://justine.storage.googleapis.com/emulator628.mp4
2020-08-27 06:08:08 +00:00
int bsr(int);
int bsrl(long);
int bsrll(long long);
int bsrmax(uintmax_t);
Add x86_64-linux-gnu emulator I wanted a tiny scriptable meltdown proof way to run userspace programs and visualize how program execution impacts memory. It helps to explain how things like Actually Portable Executable works. It can show you how the GCC generated code is going about manipulating matrices and more. I didn't feel fully comfortable with Qemu and Bochs because I'm not smart enough to understand them. I wanted something like gVisor but with much stronger levels of assurances. I wanted a single binary that'll run, on all major operating systems with an embedded GPL barrier ZIP filesystem that is tiny enough to transpile to JavaScript and run in browsers too. https://justine.storage.googleapis.com/emulator625.mp4
2020-08-25 11:23:25 +00:00
Add pseudoteletypewriter to emulator https://justine.storage.googleapis.com/emulator628.mp4
2020-08-27 06:08:08 +00:00
#define bsr(u) ((sizeof(int) * 8 - 1) ^ __builtin_clz(u))
#define bsrl(u) ((sizeof(long) * 8 - 1) ^ __builtin_clzl(u))
#define bsrll(u) ((sizeof(long long) * 8 - 1) ^ __builtin_clzll(u))
Initial import
2020-06-15 14:18:57 +00:00
COSMOPOLITAN_C_END_
#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
#endif /* COSMOPOLITAN_LIBC_NEXGEN32E_BSR_H_ */