view mercurial/bitmanipulation.h @ 38842:503f936489dd

lookup: add option to disambiguate prefix within revset

When resolving a nodeid prefix that is not unique within the repo and
the user has configured a revset that they want to disambiguate
within, we now try to look up within that revset before we fail. If
there is a unique match within the revset, we use that.

This is of course most effective at allowing a short prefix if the
revset contains few nodes. For most of our internal users at Google,
"not public()" is sufficiently small that a hex digit or two is
enough.

The implementation is currently pretty slow, but good enough for small
revsets (which is the expected use case). The scan in the revset is
linear. We may want to use a prefix tree if we want to allow users to
use a larger revset.

Credit for the idea goes to Kyle Lippincott.

Differential Revision: https://phab.mercurial-scm.org/D4037

#ifndef _HG_BITMANIPULATION_H_
#define _HG_BITMANIPULATION_H_

#include <string.h>

#include "compat.h"

static inline uint32_t getbe32(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((((uint32_t)d[0]) << 24) | (((uint32_t)d[1]) << 16) |
	        (((uint32_t)d[2]) << 8) | (d[3]));
}

static inline int16_t getbeint16(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((d[0] << 8) | (d[1]));
}

static inline uint16_t getbeuint16(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;

	return ((d[0] << 8) | (d[1]));
}

static inline void putbe32(uint32_t x, char *c)
{
	c[0] = (x >> 24) & 0xff;
	c[1] = (x >> 16) & 0xff;
	c[2] = (x >> 8) & 0xff;
	c[3] = (x)&0xff;
}

static inline double getbefloat64(const char *c)
{
	const unsigned char *d = (const unsigned char *)c;
	double ret;
	int i;
	uint64_t t = 0;
	for (i = 0; i < 8; i++) {
		t = (t << 8) + d[i];
	}
	memcpy(&ret, &t, sizeof(t));
	return ret;
}

#endif