我在具有 cortex-M7 架構的 STM32 中使用 freeRTOS CMSIS v1。我目前的目標是研究它并理解“幕后”機制（我為此目的使用除錯器）。
我試圖達到“背景關系切換”功能，但我一直無法到達那里。有可能達到嗎？要查看源代碼嗎？。
謝謝！！
uj5u.com熱心網友回復：
它是一個例外處理程式（監督呼叫處理程式）：
void xPortPendSVHandler( void )
{
/* This is a naked function. */
__asm volatile
(
" mrs r0, psp \n"
" isb \n"
" \n"
" ldr r3, pxCurrentTCBConst \n" /* Get the location of the current TCB. */
" ldr r2, [r3] \n"
" \n"
" tst r14, #0x10 \n" /* Is the task using the FPU context? If so, push high vfp registers. */
" it eq \n"
" vstmdbeq r0!, {s16-s31} \n"
" \n"
" stmdb r0!, {r4-r11, r14} \n" /* Save the core registers. */
" str r0, [r2] \n" /* Save the new top of stack into the first member of the TCB. */
" \n"
" stmdb sp!, {r0, r3} \n"
" mov r0, %0 \n"
" msr basepri, r0 \n"
" dsb \n"
" isb \n"
" bl vTaskSwitchContext \n"
" mov r0, #0 \n"
" msr basepri, r0 \n"
" ldmia sp!, {r0, r3} \n"
" \n"
" ldr r1, [r3] \n" /* The first item in pxCurrentTCB is the task top of stack. */
" ldr r0, [r1] \n"
" \n"
" ldmia r0!, {r4-r11, r14} \n" /* Pop the core registers. */
" \n"
" tst r14, #0x10 \n" /* Is the task using the FPU context? If so, pop the high vfp registers too. */
" it eq \n"
" vldmiaeq r0!, {s16-s31} \n"
" \n"
" msr psp, r0 \n"
" isb \n"
" \n"
#ifdef WORKAROUND_PMU_CM001 /* XMC4000 specific errata workaround. */
#if WORKAROUND_PMU_CM001 == 1
" push { r14 } \n"
" pop { pc } \n"
#endif
#endif
" \n"
" bx r14 \n"
" \n"
" .align 4 \n"
"pxCurrentTCBConst: .word pxCurrentTCB \n"
::"i"(configMAX_SYSCALL_INTERRUPT_PRIORITY)
);
}
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