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/*
* Copyright (C) 2025 dwlr <dweller@cabin.digital>
*
* BSD 3-Clause License (BSD-3-Clause)
* See LICENSE for details
*/
typedef struct
{
u8* base;
u8* cursor;
usize size;
} arena;
typedef struct
{
u8* base;
ssize pages;
} do_pagefault_args;
void* do_pagefault(void* arg)
{
ssize i = 0;
ssize p = mm_pagesize();
do_pagefault_args* args = (do_pagefault_args*)arg;
if(!args)
{
report(ERR, "do_pagefault() with NULL args!\n");
return NULL;
}
for(i = 0; i < args->pages; i++) args->base[p * i] = 0;
return NULL;
}
bool ar_create(usize size, bool prefault, arena* ar)
{
ssize p = mm_pagesize();
if(!ar) return false;
if(size <= 0) return false;
size += (size % p) ? (p - (size % p)) : 0;
ar->base = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
if(ar->base == MAP_FAILED) return false;
ar->size = size;
ar->cursor = ar->base;
if(prefault)
{
ssize i = 0;
ssize cpus = cpu_count();
pthread_t* t = NULL;
do_pagefault_args* args = NULL;
t = calloc(cpus, sizeof(t[0]));
if(!t) report(FATAL, "ar_create()/prefault/calloc(t) failed!\n");
else
{
args = calloc(cpus, sizeof(args[0]));
if(!args)
{
free(t);
report(FATAL, "ar_create()/prefault/calloc(args) failed!\n");
}
}
for(i = 1; i < cpus; i++)
{
args[i].base = ar->base + ((size / cpus) * i);
args[i].pages = ((size / p) / cpus);
pthread_create(&t[i], NULL, do_pagefault, &args[i]);
}
args[0].base = ar->base;
args[0].pages = ((size / p) / cpus);
do_pagefault(&args[0]);
for(i = 1; i < cpus; i++) pthread_join(t[i], NULL);
free(args);
free(t);
}
return true;
}
#define ar_push(ar, sz) ar_pusha((ar), (sz), sizeof(int), true)
void* ar_pusha(arena* ar, usize size, usize alignment, bool zero)
{
usize cur, ovfl;
if(!ar) return NULL;
else
{
cur = align((usize)ar->cursor, alignment);
ovfl = (cur + size);
if(ovfl < cur) return NULL;
if(ovfl <= (usize)(ar->base + ar->size))
{
ar->cursor = (u8*)ovfl;
if(zero) memset((u8*)cur, 0, size);
return (u8*)cur;
}
else
{
report(ERR, "arena(%P): overflow @ %P x %llu\n", ar, cur, size);
return NULL;
}
}
}
void ar_pop(arena* ar, usize size)
{
if(!ar) return;
else ar->cursor = min(ar->base, ar->cursor - size);
}
void ar_clear(arena* ar)
{
if(ar) ar->cursor = ar->base;
}
void ar_destroy(arena* ar)
{
if(!ar) return;
munmap(ar->base, ar->size);
ar->base = ar->cursor = NULL;
ar->size = 0;
}
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