From patchwork Mon Sep 10 01:27:46 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [v5,6/6] i8259: refactor pic_set_irq level logic Date: Sun, 09 Sep 2012 15:27:46 -0000 From: Matthew Ogilvie X-Patchwork-Id: 182778 Message-Id: <1347240466-6152-7-git-send-email-mmogilvi_qemu@miniinfo.net> To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Jan Kiszka , Matthew Ogilvie , "Maciej W. Rozycki" No change in functionality. Clarify that the only difference between level triggered and edge triggered interrupts is on the leading edge. Signed-off-by: Matthew Ogilvie --- hw/i8259.c | 26 +++++++++----------------- 1 file changed, 9 insertions(+), 17 deletions(-) diff --git a/hw/i8259.c b/hw/i8259.c index c011787..1ba9b3a 100644 --- a/hw/i8259.c +++ b/hw/i8259.c @@ -140,26 +140,18 @@ static void pic_set_irq(void *opaque, int irq, int level) } #endif - if (s->elcr & mask) { - /* level triggered */ - if (level) { + if (level) { + if ((s->last_irr & mask) == 0 || /* edge for edge triggered */ + (s->elcr & mask)) { /* or level triggered */ s->irr |= mask; - s->last_irr |= mask; - } else { - s->irr &= ~mask; - s->last_irr &= ~mask; } + s->last_irr |= mask; } else { - /* edge triggered */ - if (level) { - if ((s->last_irr & mask) == 0) { - s->irr |= mask; - } - s->last_irr |= mask; - } else { - s->irr &= ~mask; - s->last_irr &= ~mask; - } + /* Dropping level clears the interrupt regardless of edge trigger + * vs level trigger. + */ + s->irr &= ~mask; + s->last_irr &= ~mask; } pic_update_irq(s); }