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.section ".text"
.globl schedule
.macro preserve_ctx
cps #0x1f // Sys mode
// Store Usr regs
push {r0-r12}
push {lr}
ldr r3, =scheduler // struct Scheduler
ldr r2, [r3, #0] // struct Thread* rthread
str sp, [r2, #4] // svc_lr -> void* sp
cps #0x13 // Svc mode
mrs r1, spsr
str r1, [r2, #0xc] // preserve cpsr
str lr, [r2, #0] // svc_lr -> void* pc
.endm
.macro restore_ctx
ldr r3, =scheduler // struct Scheduler
ldr r2, [r3, #0] // struct Thread* rthread
ldr lr, [r2, #0] // void* pc -> lr_svc
ldr r0, [r2, #4] // void* sp -> r0
ldr r1, [r2, #0xc] // restore cpsr
msr spsr_f, r1
cps #0x1f // Sys mode
mov sp, r0 // Set stack pointer
// Restore Usr regs
pop {lr}
pop {r0-r12}
cps #0x13 // Svc mode
.endm
// Assumption: Enter in SVC mode
schedule:
preserve_ctx
ldr r1, =irqlr
ldr r0, [r1]
cmp r0, #0
beq 1f
// Replace LR with IRQ's LR
ldr r3, =scheduler
ldr r2, [r3, #0] // struct Thread* rthread
str r0, [r2, #0] // svc_lr -> void* pc
// Clear IRQ's LR
mov r0, #0
str r0, [r1]
1:
bl next_thread // Thread* next -> r0
ldr r3, =scheduler
ldr r2, [r3, #0] // Thread* current
cmp r0, r2 // current = next?
beq 2f
str r0, [r3, #0] // next -> rthread
2:
restore_ctx
subs pc, lr, #0
.globl cleanup
cleanup:
// roffset++
bl get_rthread_roffset
ldr r1, [r0, #0]
add r1, #1
cmp r1, #0x100 /* TQUEUE_MAX */
blo 1f
mov r1, #0
1:
str r1, [r0, #0]
// cleanup stack
svc #3
// usrloop -> rthread
ldr r3, =scheduler
ldr r2, =usrloopthread
str r2, [r3, #0]
ldr sp, [r2, #4]
ldmfd sp!,{lr}
ldmfd sp!,{r0-r12}
ldr lr, =kernel_usr_task_loop
// svc sched
svc #2
.globl kernel_usr_task_loop
kernel_usr_task_loop:
wfe
//svc #2
b kernel_usr_task_loop
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