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#include <cinttypes>
#include <cstdint>
#include <cstdio>
#include <mutex>
#include <thread>
std::mutex t1_mutex, t2_mutex;
struct test_data {
uint32_t eax;
uint32_t ebx;
struct alignas(16) {
uint8_t data[10];
} st0;
};
constexpr test_data filler = {
.eax = 0xffffffff,
.ebx = 0xffffffff,
.st0 = {{0x1f, 0x2f, 0x3f, 0x4f, 0x5f, 0x6f, 0x7f, 0x8f, 0x80, 0x40}},
};
void t_func(std::mutex &t_mutex) {
std::lock_guard<std::mutex> t_lock(t_mutex);
test_data out = filler;
asm volatile(
"finit\t\n"
"fldt %2\t\n"
"int3\n\t"
"fstpt %2\t\n"
: "+a"(out.eax), "+b"(out.ebx)
: "m"(out.st0)
: "memory", "st"
);
printf("eax = 0x%08" PRIx32 "\n", out.eax);
printf("ebx = 0x%08" PRIx32 "\n", out.ebx);
printf("st0 = { ");
for (int i = 0; i < sizeof(out.st0.data); ++i)
printf("0x%02" PRIx8 " ", out.st0.data[i]);
printf("}\n");
}
int main() {
// block both threads from proceeding
std::unique_lock<std::mutex> m1_lock(t1_mutex);
std::unique_lock<std::mutex> m2_lock(t2_mutex);
// start both threads
std::thread t1(t_func, std::ref(t1_mutex));
std::thread t2(t_func, std::ref(t2_mutex));
// release lock on thread 1 to make it interrupt the program
m1_lock.unlock();
// wait for thread 1 to finish
t1.join();
// release lock on thread 2
m2_lock.unlock();
// wait for thread 2 to finish
t2.join();
return 0;
}
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