arch/sh/lib/udivsi3_i4i-Os.S

Source file repositories/reference/linux-study-clean/arch/sh/lib/udivsi3_i4i-Os.S

File Facts

System
Linux kernel
Corpus path
arch/sh/lib/udivsi3_i4i-Os.S
Extension
.S
Size
2315 bytes
Lines
129
Domain
Architecture Layer
Bucket
arch/sh
Inferred role
Architecture Layer: arch/sh
Status
atlas-only

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

STMicroelectronics ST40 CPUs.
   Contributed by J"orn Rennecke joern.rennecke@st.com.  */

/* Size: 186 bytes jointly for udivsi3_i4i and sdivsi3_i4i
   sh4-200 run times:
   udiv small divisor: 55 cycles
   udiv large divisor: 52 cycles
   sdiv small divisor, positive result: 59 cycles
   sdiv large divisor, positive result: 56 cycles
   sdiv small divisor, negative result: 65 cycles (*)
   sdiv large divisor, negative result: 62 cycles (*)
   (*): r2 is restored in the rts delay slot and has a lingering latency
        of two more cycles.  */
	.balign 4
	.global	__udivsi3_i4i
	.global	__udivsi3_i4
	.set	__udivsi3_i4, __udivsi3_i4i
	.type	__udivsi3_i4i, @function
	.type	__sdivsi3_i4i, @function
__udivsi3_i4i:
	sts pr,r1
	mov.l r4,@-r15
	extu.w r5,r0
	cmp/eq r5,r0
	swap.w r4,r0
	shlr16 r4
	bf/s large_divisor
	div0u
	mov.l r5,@-r15
	shll16 r5
sdiv_small_divisor:
	div1 r5,r4
	bsr div6
	div1 r5,r4
	div1 r5,r4
	bsr div6
	div1 r5,r4
	xtrct r4,r0
	xtrct r0,r4
	bsr div7
	swap.w r4,r4
	div1 r5,r4
	bsr div7
	div1 r5,r4
	xtrct r4,r0
	mov.l @r15+,r5
	swap.w r0,r0
	mov.l @r15+,r4
	jmp @r1
	rotcl r0
div7:
	div1 r5,r4
div6:
	            div1 r5,r4; div1 r5,r4; div1 r5,r4
	div1 r5,r4; div1 r5,r4; rts;        div1 r5,r4

divx3:
	rotcl r0
	div1 r5,r4
	rotcl r0
	div1 r5,r4
	rotcl r0
	rts
	div1 r5,r4

large_divisor:
	mov.l r5,@-r15
sdiv_large_divisor:
	xor r4,r0
	.rept 4

Annotation

Implementation Notes