// Copyright 2017 plutoo
#include <switch.h>
#include <malloc.h>
#include "../internal.h"

extern const u8 __tdata_lma[];
extern const u8 __tdata_lma_end[];
extern u8 __tls_start[];
extern u8 __tls_end[];

// Thread creation args; keep this struct's size 16-byte aligned
typedef struct {
    Thread*        t;
    ThreadFunc     entry;
    void*          arg;
    struct _reent* reent;
    void*          tls;
    void*          padding;
} ThreadEntryArgs;

static void _EntryWrap(ThreadEntryArgs* args) {
    // Initialize thread vars
    ThreadVars* tv = getThreadVars();
    tv->magic      = THREADVARS_MAGIC;
    tv->thread_ptr = args->t;
    tv->reent      = args->reent;
    tv->tls_tp     = (u8*)args->tls-2*sizeof(void*); // subtract size of Thread Control Block (TCB)
    tv->handle     = args->t->handle;

    // Launch thread entrypoint
    args->entry(args->arg);
    svcExitThread();
}

Result threadCreate(
    Thread* t, ThreadFunc entry, void* arg, size_t stack_sz, int prio,
    int cpuid)
{
    stack_sz = (stack_sz+0xFFF) &~ 0xFFF;

    Result rc = 0;
    size_t reent_sz = (sizeof(struct _reent)+0xF) &~ 0xF;
    size_t tls_sz = (__tls_end-__tls_start+0xF) &~ 0xF;
    void*  stack = memalign(0x1000, stack_sz + reent_sz + tls_sz);

    if (stack == NULL) {
        rc = MAKERESULT(MODULE_LIBNX, LIBNX_OUTOFMEM);
    }
    else {
        // todo: svcMapMemory returns 0xDC01
        void* stack_mirror = stack;//virtmemReserveMap(stack_sz);
        //rc = svcMapMemory(stack_mirror, stack, stack_sz);

        if (R_SUCCEEDED(rc))
        {
            u64 stack_top = ((u64)stack_mirror) + t->stack_sz - sizeof(ThreadEntryArgs);
            ThreadEntryArgs* args = (ThreadEntryArgs*) stack_top;
            Handle handle;

            rc = svcCreateThread(
                &handle, (ThreadFunc) &_EntryWrap, args, (void*)stack_top,
                prio, cpuid);

            if (R_SUCCEEDED(rc))
            {
                t->handle = handle;
                t->stack_mem = stack;
                t->stack_mirror = stack_mirror;
                t->stack_sz = stack_sz;

                args->t = t;
                args->entry = entry;
                args->arg = arg;
                args->reent = (struct _reent*)((u8*)stack + stack_sz);
                args->tls = (u8*)stack + stack_sz + reent_sz;

                // Set up child thread's reent struct, inheriting standard file handles
                _REENT_INIT_PTR(args->reent);
                struct _reent* cur = getThreadVars()->reent;
                args->reent->_stdin  = cur->_stdin;
                args->reent->_stdout = cur->_stdout;
                args->reent->_stderr = cur->_stderr;

                // Set up child thread's TLS segment
                size_t tls_load_sz = __tdata_lma_end-__tdata_lma;
                size_t tls_bss_sz = tls_sz - tls_load_sz;
                if (tls_load_sz)
                    memcpy(args->tls, __tdata_lma, tls_load_sz);
                if (tls_bss_sz)
                    memset(args->tls+tls_load_sz, 0, tls_bss_sz);
            }

            if (R_FAILED(rc)) {
                svcUnmapMemory(stack_mirror, stack, stack_sz);
            }
        }

        if (R_FAILED(rc)) {
            virtmemFreeMap(stack_mirror, stack_sz);
            free(stack);
        }
    }

    return rc;
}

Result threadStart(Thread* t) {
    return svcStartThread(t->handle);
}

Result threadWaitForExit(Thread* t) {
    Handle handle = t->handle;
    s32    idx = 0;
    return svcWaitSynchronization(&idx, &handle, 1, -1);
}

Result threadClose(Thread* t) {
    Result rc;

    rc = svcUnmapMemory(t->stack_mirror, t->stack_mem, t->stack_sz);
    virtmemFreeMap(t->stack_mirror, t->stack_sz);
    free(t->stack_mem);
    svcCloseHandle(t->handle);

    return rc;
}