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/* This file is allowed to be undocumented as it is only temporarily in this
* tree. At some point in the (hopefully) near future, I intend to move the
* kernel code and initrd generation stuff into separate repositories, to make
* things easier for myself. For now though, this is good enough.
*/
/* compile with riscv64-unknown-elf-gcc -ffreestanding -nostdlib */
/* create initrd with echo init | cpio -H newc -o > initrd */
#include <stdint.h>
#include "../../../include/apos/syscalls.h"
#define ecall() do { asm ("ecall" : : : "a0", "a1", "a2", "a3", "a4", "a5"); \
} while (0)
static void sys_noop()
{
long register a0 asm ("a0") = SYS_NOOP;
ecall();
}
static void sys_putch(char c)
{
long register a0 asm ("a0") = SYS_PUTCH;
long register a1 asm ("a1") = c;
ecall();
}
static uint64_t sys_timebase()
{
long register a0 asm ("a0") = SYS_TIMEBASE;
long register a1 asm ("a1") = 0;
long register a2 asm ("a2") = 0;
ecall();
#if defined(_LP64)
return a1;
#else
uint64_t t = a1;
t <<= 32;
return t + a2;
#endif
}
static uint64_t sys_ticks()
{
long register a0 asm ("a0") = SYS_TICKS;
long register a1 asm ("a1") = 0;
long register a2 asm ("a2") = 0;
ecall();
#if defined(_LP64)
return a1;
#else
uint64_t t = a1;
t <<= 32;
return t + a2;
#endif
}
static void puts(const char *s)
{
while (*s)
sys_putch(*s++);
}
static void _print_number(uint64_t v)
{
if (v == 0)
return;
_print_number(v / 10);
sys_putch((v % 10) + '0');
}
static void print_number(uint64_t v)
{
if (v == 0) {
sys_putch('0');
return;
}
_print_number(v);
}
static void print_value(const char *s, uint64_t v)
{
puts(s);
puts(": ");
print_number(v);
sys_putch('\n');
}
static uint64_t sys_fork()
{
long register a0 asm ("a0") = SYS_FORK;
long register a1 asm ("a1") = 0;
ecall();
if (a0 != 0)
print_value("fork() failed with error ", a0);
return a1;
}
static uint64_t sys_swap(long tid)
{
long register a0 asm ("a0") = SYS_SWAP;
long register a1 asm ("a1") = tid;
ecall();
if (a0 != 0)
print_value("swap() failed with error ", a0);
return a0;
}
void _start()
{
sys_noop();
puts("Hello, world!\n");
uint64_t second = sys_timebase();
print_value("Timebase", second);
uint64_t n = 0, i, start;
start = i = sys_ticks();
print_value("Start ticks", start);
while (i < start + second) {
i = sys_ticks();
n++;
}
print_value("End ticks", i);
print_value("Syscalls per second", n);
puts("Starting fork():\n");
long pid = sys_fork();
if (pid != 0) {
print_value("Child pid: ", pid);
puts("Swapping to child...\n");
while(1) sys_swap(pid);
}
puts("Hello from child!\n");
puts("Doing 1M swaps...\n");
start = sys_ticks();
for (long i = 0; i < 1000000; ++i)
sys_swap(1);
uint64_t ticks = sys_ticks() - start;
print_value("1M swaps took ", ticks / second);
}
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