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Embedded FreeBSD Cookbook phần 5

Cuộc gọi hệ thống được chứa trong cơ cấu sysent, được định nghĩa trong / sys / kern / init_sysent.c. Khi một cuộc gọi KLD hệ thống được thực hiện, một mục mới được thêm vào cấu trúc hạt nhân toàn cầu sysent. Ví dụ 3-8 chứa một danh sách một phần của cấu trúc sysent. / * Các diễn viên không có thật nhưng sẽ làm cho bây giờ. * / Struct sysent | 86 Embedded FreeBSD Cookbook and PCI interrupt disable. Each bit of the Interrupt Status register is defined in Table 5-6. Bit Description Value 0 Interrupt Enable 0 disabled 1 enabled 1 Interrupt Polarity 0 active low 1 active high 2 Interrupt Status 0 interrupt not active 1 interrupt active 3 Reserved NA 4 Reserved NA 5 Reserved NA 6 PCI Interrupt Enable 0 disabled 1 enabled 7 Reserved NA 8 Reserved NA 9 Reserved NA 10 Interrupt Clear Writing a 1 clears this interrupt 31 11 Reserved NA Table 5-6. Interrupt Status Register The Interrupt Status Register contains bits that program the controller interrupt enable and disable the controller interrupt and provide the interrupt status. The interrupt enable bit bit 0 enables or disables the controller interrupt when set to 1 the interrupt is enabled otherwise it is disabled. Interrupt polarity bit bit 1 controls the type of interrupt. This bit controls on which edge the interrupt is active low to high transition or high to low transition. The default is active high. The interrupt status bit bit 2 provides us with a status bit to determine if an interrupt is active. The PCI interrupt bit bit 6 controls the PCI interrupt enable. A value of 1 enables PCI interrupts 0 disables the PCI interrupts. Writing to the Interrupt clear bit 10 clears a pending interrupt. 87 Chapter Five Midlevel Interface Library The DIO24 Application Interface Library The implementation of the DIO24 Interface library consists of four functional categories. Each functional category is related to programming the different features of the controller. The categories are register utilities reading and writing the digital IO lines programming the configuration register and programming the interrupt controller. Each of the following sections addresses the functions for the functional category. The dio_get and dio_set Functions All accesses to the PCI-DIO24 hardware registers are provided by two internal library functions dio_get and dio_set. These two .