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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "runtime.h"
#include "defs_GOOS_GOARCH.h"
#include "os_GOOS.h"
#include "textflag.h"
#define AT_NULL 0
#define AT_PLATFORM 15 // introduced in at least 2.6.11
#define AT_HWCAP 16 // introduced in at least 2.6.11
#define AT_RANDOM 25 // introduced in 2.6.29
#define HWCAP_VFP (1 << 6) // introduced in at least 2.6.11
#define HWCAP_VFPv3 (1 << 13) // introduced in 2.6.30
static uint32 runtime·randomNumber;
uint8 runtime·armArch = 6; // we default to ARMv6
uint32 runtime·hwcap; // set by setup_auxv
extern uint8 runtime·goarm; // set by 5l
void
runtime·checkgoarm(void)
{
if(runtime·goarm > 5 && !(runtime·hwcap & HWCAP_VFP)) {
runtime·printf("runtime: this CPU has no floating point hardware, so it cannot run\n");
runtime·printf("this GOARM=%d binary. Recompile using GOARM=5.\n", runtime·goarm);
runtime·exit(1);
}
if(runtime·goarm > 6 && !(runtime·hwcap & HWCAP_VFPv3)) {
runtime·printf("runtime: this CPU has no VFPv3 floating point hardware, so it cannot run\n");
runtime·printf("this GOARM=%d binary. Recompile using GOARM=6.\n", runtime·goarm);
runtime·exit(1);
}
}
#pragma textflag NOSPLIT
void
runtime·setup_auxv(int32 argc, byte **argv)
{
byte **envp;
byte *rnd;
uint32 *auxv;
uint32 t;
// skip envp to get to ELF auxiliary vector.
for(envp = &argv[argc+1]; *envp != nil; envp++)
;
envp++;
for(auxv=(uint32*)envp; auxv[0] != AT_NULL; auxv += 2) {
switch(auxv[0]) {
case AT_RANDOM: // kernel provided 16-byte worth of random data
if(auxv[1]) {
rnd = (byte*)auxv[1];
runtime·randomNumber = rnd[4] | rnd[5]<<8 | rnd[6]<<16 | rnd[7]<<24;
}
break;
case AT_PLATFORM: // v5l, v6l, v7l
if(auxv[1]) {
t = *(uint8*)(auxv[1]+1);
if(t >= '5' && t <= '7')
runtime·armArch = t - '0';
}
break;
case AT_HWCAP: // CPU capability bit flags
runtime·hwcap = auxv[1];
break;
}
}
}
#pragma textflag NOSPLIT
int64
runtime·cputicks(void)
{
// Currently cputicks() is used in blocking profiler and to seed runtime·fastrand1().
// runtime·nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
// runtime·randomNumber provides better seeding of fastrand1.
return runtime·nanotime() + runtime·randomNumber;
}
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