circuitpython/py/nlrx86.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2013-2017 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "py/mpconfig.h"
#include "py/mpstate.h"
#include "py/nlr.h"

#if !MICROPY_NLR_SETJMP && defined(__i386__)

#undef nlr_push

// For reference, x86 callee save regs are:
//  ebx, esi, edi, ebp, esp, eip

#if defined(_WIN32) || defined(__CYGWIN__)
#define NLR_OS_WINDOWS 1
#else
#define NLR_OS_WINDOWS 0
#endif

#if NLR_OS_WINDOWS
unsigned int nlr_push_tail(nlr_buf_t *nlr) asm("nlr_push_tail");
#else
__attribute__((used)) unsigned int nlr_push_tail(nlr_buf_t *nlr);
#endif

unsigned int nlr_push(nlr_buf_t *nlr) {
    (void)nlr;

    __asm volatile (
    // Check for Zephyr, which uses a different calling convention
    // by default.
    // TODE: Better support for various x86 calling conventions
    // (unfortunately, __attribute__((naked)) is not supported on x86).
    #if !(defined(__ZEPHYR__) || defined(__ANDROID__))
    "pop    %ebp                \n" // undo function's prelude
    #endif
    "mov    4(%esp), %edx       \n" // load nlr_buf
    "mov    (%esp), %eax        \n" // load return %eip
    "mov    %eax, 8(%edx)       \n" // store %eip into nlr_buf
    "mov    %ebp, 12(%edx)      \n" // store %ebp into nlr_buf
    "mov    %esp, 16(%edx)      \n" // store %esp into nlr_buf
    "mov    %ebx, 20(%edx)      \n" // store %ebx into nlr_buf
    "mov    %edi, 24(%edx)      \n" // store %edi into nlr_buf
    "mov    %esi, 28(%edx)      \n" // store %esi into nlr_buf
    "jmp    nlr_push_tail       \n" // do the rest in C
    );

    return 0; // needed to silence compiler warning
}

__attribute__((used)) unsigned int nlr_push_tail(nlr_buf_t *nlr) {
    nlr_buf_t **top = &MP_STATE_THREAD(nlr_top);
    nlr->prev = *top;
    *top = nlr;
    return 0; // normal return
}

void nlr_pop(void) {
    nlr_buf_t **top = &MP_STATE_THREAD(nlr_top);
    *top = (*top)->prev;
}

NORETURN void nlr_jump(void *val) {
    nlr_buf_t **top_ptr = &MP_STATE_THREAD(nlr_top);
    nlr_buf_t *top = *top_ptr;
    if (top == NULL) {
        nlr_jump_fail(val);
    }

    top->ret_val = val;
    *top_ptr = top->prev;

    __asm volatile (
    "mov    %0, %%edx           \n" // %edx points to nlr_buf
    "mov    28(%%edx), %%esi    \n" // load saved %esi
    "mov    24(%%edx), %%edi    \n" // load saved %edi
    "mov    20(%%edx), %%ebx    \n" // load saved %ebx
    "mov    16(%%edx), %%esp    \n" // load saved %esp
    "mov    12(%%edx), %%ebp    \n" // load saved %ebp
    "mov    8(%%edx), %%eax     \n" // load saved %eip
    "mov    %%eax, (%%esp)      \n" // store saved %eip to stack
    "xor    %%eax, %%eax        \n" // clear return register
    "inc    %%al                \n" // increase to make 1, non-local return
    "ret                        \n" // return
    :                               // output operands
    : "r"(top)                      // input operands
    :                               // clobbered registers
    );

    for (;;); // needed to silence compiler warning
}

#endif // !MICROPY_NLR_SETJMP && defined(__i386__)