X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?a=blobdiff_plain;f=src%2Fintr_asm.S;fp=src%2Fintr_asm.S;h=ea0be36d1561b53a3f6a32bce77371b065d782b1;hb=a2f94f569a4c99204de02814a20098a71527e913;hp=0000000000000000000000000000000000000000;hpb=d1e8a437c1fab4535f82c4c214ec3330ac32e48d;p=bootcensus

diff --git a/src/intr_asm.S b/src/intr_asm.S
new file mode 100644
index 0000000..ea0be36
--- /dev/null
+++ b/src/intr_asm.S
@@ -0,0 +1,114 @@
+	.data
+	.align 4
+	.short 0
+idtr_desc:
+lim:	.short 0
+addr:	.long 0
+
+	.text
+/* void set_idt(uint32_t addr, uint16_t limit) */
+	.global set_idt
+set_idt:
+	mov 4(%esp), %eax
+	mov %eax, addr
+	mov 8(%esp), %ax
+	mov %ax, lim
+	lidt (idtr_desc)
+	ret
+
+/* int get_intr_flag() */
+	.global get_intr_flag
+get_intr_flag:
+	pushf
+	popl %eax
+	# bit 9 of eflags is IF
+	shr $9, %eax
+	and $1, %eax
+	ret
+
+/* void set_intr_flag(int onoff) */
+	.global set_intr_flag
+set_intr_flag:
+	cmpl $0, 4(%esp)
+	jz 0f
+	sti
+	ret
+0:	cli
+	ret
+
+/* interrupt entry with error code macro
+ * this macro generates an interrupt entry point for the
+ * exceptions which include error codes in the stack frame
+ */
+	.macro ientry_err n name
+	.globl intr_entry_\name
+intr_entry_\name:
+	pushl $\n
+	jmp intr_entry_common
+	.endm
+
+/* interrupt entry without error code macro
+ * this macro generates an interrupt entry point for the interrupts
+ * and exceptions which do not include error codes in the stack frame
+ * it pushes a dummy error code (0), to make the stack frame identical
+ */
+	.macro ientry_noerr n name
+	.globl intr_entry_\name
+intr_entry_\name:
+	pushl $0
+	pushl $\n
+	jmp intr_entry_common
+	.endm
+
+/* common code used by all entry points. calls dispatch_intr()
+ * defined in intr.c
+ */
+	.extern dispatch_intr
+intr_entry_common:
+	/* save general purpose registers */
+	pusha
+	call dispatch_intr
+intr_ret_local:
+	/* restore general purpose registers */
+	popa
+	/* remove error code and intr num from stack */
+	add $8, %esp
+	iret
+
+/* special case for the timer interrupt, to avoid all the overhead of
+ * going through the C interrupt dispatcher 250 times each second
+ */
+	.extern nticks
+	.global intr_entry_fast_timer
+intr_entry_fast_timer:
+	incl nticks
+	# signal end of interrupt
+	push %eax
+	mov $0x20, %al
+	out %al, $0x20
+	pop %eax
+	iret
+	
+
+/* XXX not necessary for now, just leaving it in in case it's useful
+ * down the road.
+ *
+ * intr_ret is called by context_switch to return from the kernel
+ * to userspace. The argument is a properly formed intr_frame
+ * structure with the saved context of the new task.
+ *
+ * First thing to do is remove the return address pointing back
+ * to context_switch, which then leaves us with a proper interrupt
+ * stack frame, so we can jump right in the middle of the regular
+ * interrupt return code above.
+ */
+	.global intr_ret
+intr_ret:
+	add $4, %esp
+	jmp intr_ret_local
+
+/* by including interrupts.h with ASM defined, the macros above
+ * are expanded to generate all required interrupt entry points
+ */
+#define ASM
+#include <intrtab.h>