ARMask.The ARM has six operating modes:
• User (unprivileged mode under which most tasks run)
• FIQ (entered when a high priority (fast) interrupt is raised)
• IRQ (entered when a low priority (normal) interrupt is raised)
• Supervisor (entered on reset and when a Software Interrupt instruction is
executed)
• Abort (used to handle memory access violations)
• Undef (used to handle undefined instructions)
* ARM Architecture Version 4 adds a seventh mode:
• System (privileged mode using the same registers as user mode)
樣板 B 樹 ( B - tree )
規(guī)則 :
(1) 每個節(jié)點內元素個數在 [MIN,2*MIN] 之間, 但根節(jié)點元素個數為 [1,2*MIN]
(2) 節(jié)點內元素由小排到大, 元素不重複
(3) 每個節(jié)點內的指標個數為元素個數加一
(4) 第 i 個指標所指向的子節(jié)點內的所有元素值皆小於父節(jié)點的第 i 個元素
(5) B 樹內的所有末端節(jié)點深度一樣
