98 lines
2.1 KiB
C
98 lines
2.1 KiB
C
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#include "tb_cxxrtl_io.h"
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#include "hazard3_irq.h"
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// - Foreground code pends the top-half handler, at maximum priority
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// - Each time the top-half handler is called, it installs a bottom half at
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// the next descending priority
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// - Each bottom half hander re-pends the top half handler (which immediately
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// preempts it) to set the next lower-numbered bottom handler
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// - When top returns to bottom, and that bottom returns to the *next* bottom,
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// which re-pends the top
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// - So on until all handlers have fired
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// - This should stack within two exception frames and enter the EIRQ vector
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// exactly 16 times (one for each time the top handler runs)
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void handler_top() {
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static int next_bottom = MAX_PRIORITY - 1;
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tb_puts("Top\n");
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if (next_bottom >= 0) {
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h3irq_force_pending(next_bottom--, true);
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}
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}
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void handler_bottom() {
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int irqnum = h3irq_get_current_irq();
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tb_printf("Enter bottom %d\n", irqnum);
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h3irq_force_pending(MAX_PRIORITY, true);
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tb_printf("Exit bottom %d\n", irqnum);
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}
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int main() {
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global_irq_enable(true);
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external_irq_enable(true);
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// Set up one IRQ at each priority
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for (int i = 0; i <= MAX_PRIORITY; ++i) {
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h3irq_enable(i, true);
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h3irq_set_priority(i, i);
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h3irq_set_handler(i, i == MAX_PRIORITY ? handler_top : handler_bottom);
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}
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h3irq_force_pending(MAX_PRIORITY, true);
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tb_printf("EIRQ vector was entered %d times\n", _external_irq_entry_count);
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return 0;
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}
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/*EXPECTED-OUTPUT***************************************************************
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Top
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Enter bottom 14
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Top
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Exit bottom 14
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Enter bottom 13
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Top
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Exit bottom 13
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Enter bottom 12
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Top
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Exit bottom 12
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Enter bottom 11
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Top
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Exit bottom 11
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Enter bottom 10
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Top
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Exit bottom 10
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Enter bottom 9
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Top
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Exit bottom 9
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Enter bottom 8
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Top
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Exit bottom 8
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Enter bottom 7
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Top
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Exit bottom 7
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Enter bottom 6
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Top
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Exit bottom 6
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Enter bottom 5
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Top
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Exit bottom 5
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Enter bottom 4
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Top
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Exit bottom 4
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Enter bottom 3
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Top
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Exit bottom 3
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Enter bottom 2
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Top
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Exit bottom 2
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Enter bottom 1
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Top
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Exit bottom 1
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Enter bottom 0
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Top
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Exit bottom 0
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EIRQ vector was entered 16 times
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*******************************************************************************/
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