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New gcc branch

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master
Jonathan Protzenko 8 years ago
parent 3ef5901c5b
commit 753d6965f5
2 changed files with 48 additions and 235 deletions
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96
source/CortexContextSwitch.s
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@ -1,20 +1,22 @@
AREA asm_func, CODE, READONLY
.syntax unified
.cpu cortex-m0
.thumb
.text
.align 2
; Export our context switching subroutine as a C function for use in mBed
EXPORT swap_context
EXPORT save_context
@ Export our context switching subroutine as a C function for use in mBed
.global swap_context
.global save_context
ALIGN
; R0 Contains a pointer to the TCB of the fibre being scheduled out.
; R1 Contains a pointer to the TCB of the fibre being scheduled in.
; R2 Contains a pointer to the base of the stack of the fibre being scheduled out.
; R3 Contains a pointer to the base of the stack of the fibre being scheduled in.
@ R0 Contains a pointer to the TCB of the fibre being scheduled out.
@ R1 Contains a pointer to the TCB of the fibre being scheduled in.
@ R2 Contains a pointer to the base of the stack of the fibre being scheduled out.
@ R3 Contains a pointer to the base of the stack of the fibre being scheduled in.
swap_context
swap_context:
; Write our core registers into the TCB
; First, store the general registers
@ Write our core registers into the TCB
@ First, store the general registers
STR R0, [R0,#0]
STR R1, [R0,#4]
@ -25,7 +27,7 @@ swap_context
STR R6, [R0,#24]
STR R7, [R0,#28]
; Now the high general purpose registers
@ Now the high general purpose registers
MOV R4, R8
STR R4, [R0,#32]
MOV R4, R9
@ -37,25 +39,25 @@ swap_context
MOV R4, R12
STR R4, [R0,#48]
; Now the Stack and Link Register.
; As this context is only intended for use with a fiber scheduler,
; we don't need the PC.
@ Now the Stack and Link Register.
@ As this context is only intended for use with a fiber scheduler,
@ we don't need the PC.
MOV R6, SP
STR R6, [R0,#52]
MOV R4, LR
STR R4, [R0,#56]
; Finally, Copy the stack. We do this to reduce RAM footprint, as stackis usually very small at the point
; of sceduling, but we need a lot of capacity for interrupt handling and other functions.
@ Finally, Copy the stack. We do this to reduce RAM footprint, as stackis usually very small at the point
@ of sceduling, but we need a lot of capacity for interrupt handling and other functions.
MOVS R7, #0x20 ; Load R8 with top of System Stack space.
MOVS R7, #0x20 @ Load R8 with top of System Stack space.
LSLS R7, #24
MOVS R4, #0x40
LSLS R4, #8
ORRS R7, R4
MOV R4, R7
store_stack
store_stack:
SUBS R4, #4
SUBS R2, #4
@ -65,22 +67,22 @@ store_stack
CMP R4, R6
BNE store_stack
;
; Now page in the new context.
; Update all registers except the PC. We can also safely ignore the STATUS register, as we're just a fiber scheduler.
;
@
@ Now page in the new context.
@ Update all registers except the PC. We can also safely ignore the STATUS register, as we're just a fiber scheduler.
@
LDR R4, [R1, #56]
MOV LR, R4
LDR R6, [R1, #52]
MOV SP, R6
; Copy the stack in.
; n.b. we do this after setting the SP to make comparisons easier.
@ Copy the stack in.
@ n.b. we do this after setting the SP to make comparisons easier.
MOV R4, R7 ; Load R4 with top of System Stack space.
MOV R4, R7 @ Load R4 with top of System Stack space.
restore_stack
restore_stack:
SUBS R4, #4
SUBS R3, #4
@ -110,19 +112,19 @@ restore_stack
LDR R0, [R1, #0]
LDR R1, [R1, #4]
; Return to caller (scheduler).
@ Return to caller (scheduler).
BX LR
; R0 Contains a pointer to the TCB of the fibre to snapshot
; R1 Contains a pointer to the base of the stack of the fibre being snapshotted
@ R0 Contains a pointer to the TCB of the fibre to snapshot
@ R1 Contains a pointer to the base of the stack of the fibre being snapshotted
save_context
save_context:
; Write our core registers into the TCB
; First, store the general registers
@ Write our core registers into the TCB
@ First, store the general registers
STR R0, [R0,#0]
STR R1, [R0,#4]
@ -133,7 +135,7 @@ save_context
STR R6, [R0,#24]
STR R7, [R0,#28]
; Now the high general purpose registers
@ Now the high general purpose registers
MOV R4, R8
STR R4, [R0,#32]
MOV R4, R9
@ -145,25 +147,25 @@ save_context
MOV R4, R12
STR R4, [R0,#48]
; Now the Stack and Link Register.
; As this context is only intended for use with a fiber scheduler,
; we don't need the PC.
@ Now the Stack and Link Register.
@ As this context is only intended for use with a fiber scheduler,
@ we don't need the PC.
MOV R6, SP
STR R6, [R0,#52]
MOV R4, LR
STR R4, [R0,#56]
; Finally, Copy the stack. We do this to reduce RAM footprint, as stackis usually very small at the point
; of sceduling, but we need a lot of capacity for interrupt handling and other functions.
@ Finally, Copy the stack. We do this to reduce RAM footprint, as stackis usually very small at the point
@ of sceduling, but we need a lot of capacity for interrupt handling and other functions.
MOVS R5, #0x20 ; Load R8 with top of System Stack space.
MOVS R5, #0x20 @ Load R8 with top of System Stack space.
LSLS R5, #24
MOVS R4, #0x40
LSLS R4, #8
ORRS R5, R4
MOV R4, R5
store_stack1
store_stack1:
SUBS R4, #4
SUBS R1, #4
@ -173,15 +175,13 @@ store_stack1
CMP R4, R6
BNE store_stack1
; Restore scratch registers.
@ Restore scratch registers.
LDR R7, [R0, #28]
LDR R6, [R0, #24]
LDR R5, [R0, #20]
LDR R4, [R0, #16]
; Return to caller (scheduler).
@ Return to caller (scheduler).
BX LR
ALIGN
END

187
source/CortexContextSwitch.s.gcc
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@ -1,187 +0,0 @@
.syntax unified
.cpu cortex-m0
.thumb
.text
.align 2
@ Export our context switching subroutine as a C function for use in mBed
.global swap_context
.global save_context
@ R0 Contains a pointer to the TCB of the fibre being scheduled out.
@ R1 Contains a pointer to the TCB of the fibre being scheduled in.
@ R2 Contains a pointer to the base of the stack of the fibre being scheduled out.
@ R3 Contains a pointer to the base of the stack of the fibre being scheduled in.
swap_context:
@ Write our core registers into the TCB
@ First, store the general registers
STR R0, [R0,#0]
STR R1, [R0,#4]
STR R2, [R0,#8]
STR R3, [R0,#12]
STR R4, [R0,#16]
STR R5, [R0,#20]
STR R6, [R0,#24]
STR R7, [R0,#28]
@ Now the high general purpose registers
MOV R4, R8
STR R4, [R0,#32]
MOV R4, R9
STR R4, [R0,#36]
MOV R4, R10
STR R4, [R0,#40]
MOV R4, R11
STR R4, [R0,#44]
MOV R4, R12
STR R4, [R0,#48]
@ Now the Stack and Link Register.
@ As this context is only intended for use with a fiber scheduler,
@ we don't need the PC.
MOV R6, SP
STR R6, [R0,#52]
MOV R4, LR
STR R4, [R0,#56]
@ Finally, Copy the stack. We do this to reduce RAM footprint, as stackis usually very small at the point
@ of sceduling, but we need a lot of capacity for interrupt handling and other functions.
MOVS R7, #0x20 @ Load R8 with top of System Stack space.
LSLS R7, #24
MOVS R4, #0x40
LSLS R4, #8
ORRS R7, R4
MOV R4, R7
store_stack:
SUBS R4, #4
SUBS R2, #4
LDR R5, [R4]
STR R5, [R2]
CMP R4, R6
BNE store_stack
@
@ Now page in the new context.
@ Update all registers except the PC. We can also safely ignore the STATUS register, as we're just a fiber scheduler.
@
LDR R4, [R1, #56]
MOV LR, R4
LDR R6, [R1, #52]
MOV SP, R6
@ Copy the stack in.
@ n.b. we do this after setting the SP to make comparisons easier.
MOV R4, R7 @ Load R4 with top of System Stack space.
restore_stack:
SUBS R4, #4
SUBS R3, #4
LDR R5, [R3]
STR R5, [R4]
CMP R4, R6
BNE restore_stack
LDR R4, [R1, #48]
MOV R12, R4
LDR R4, [R1, #44]
MOV R11, R4
LDR R4, [R1, #40]
MOV R10, R4
LDR R4, [R1, #36]
MOV R9, R4
LDR R4, [R1, #32]
MOV R8, R4
LDR R7, [R1, #28]
LDR R6, [R1, #24]
LDR R5, [R1, #20]
LDR R4, [R1, #16]
LDR R3, [R1, #12]
LDR R2, [R1, #8]
LDR R0, [R1, #0]
LDR R1, [R1, #4]
@ Return to caller (scheduler).
BX LR
@ R0 Contains a pointer to the TCB of the fibre to snapshot
@ R1 Contains a pointer to the base of the stack of the fibre being snapshotted
save_context:
@ Write our core registers into the TCB
@ First, store the general registers
STR R0, [R0,#0]
STR R1, [R0,#4]
STR R2, [R0,#8]
STR R3, [R0,#12]
STR R4, [R0,#16]
STR R5, [R0,#20]
STR R6, [R0,#24]
STR R7, [R0,#28]
@ Now the high general purpose registers
MOV R4, R8
STR R4, [R0,#32]
MOV R4, R9
STR R4, [R0,#36]
MOV R4, R10
STR R4, [R0,#40]
MOV R4, R11
STR R4, [R0,#44]
MOV R4, R12
STR R4, [R0,#48]
@ Now the Stack and Link Register.
@ As this context is only intended for use with a fiber scheduler,
@ we don't need the PC.
MOV R6, SP
STR R6, [R0,#52]
MOV R4, LR
STR R4, [R0,#56]
@ Finally, Copy the stack. We do this to reduce RAM footprint, as stackis usually very small at the point
@ of sceduling, but we need a lot of capacity for interrupt handling and other functions.
MOVS R5, #0x20 @ Load R8 with top of System Stack space.
LSLS R5, #24
MOVS R4, #0x40
LSLS R4, #8
ORRS R5, R4
MOV R4, R5
store_stack1:
SUBS R4, #4
SUBS R1, #4
LDR R5, [R4]
STR R5, [R1]
CMP R4, R6
BNE store_stack1
@ Restore scratch registers.
LDR R7, [R0, #28]
LDR R6, [R0, #24]
LDR R5, [R0, #20]
LDR R4, [R0, #16]
@ Return to caller (scheduler).
BX LR
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