mirror of
https://github.com/sigmasternchen/chaOS
synced 2025-03-15 05:38:54 +00:00
432 lines
No EOL
9.5 KiB
NASM
432 lines
No EOL
9.5 KiB
NASM
;; scheduler
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;
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; Because we want want to be able use multible thread, we need a scheduler.
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; This scheduler is supposed to support up to 4 threads.
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;
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;;
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;; global memory map
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;
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; $0000
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; G P R
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; $001F
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; $0020
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; I O R
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; $005F
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; $0060
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; external I O R
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; $00FF
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; $0100
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; SRAM
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; $0100
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; 164 bytes of scheduler memory
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; $01A3
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; $01A4
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; 15,710 bytes of heap
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; $3EFF
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; $3F00
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; 512 bytes of stack
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; $40FF
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; $40FF
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;
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;;
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; this a ATmega1284P specific
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.equ heap_start = 0x01A3 ; starting address of heap
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.equ heap_end = 0x3EFF ; ending address of heap
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.equ scheduler_global_active = 0x0100 ; address of active-thread-cell
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.equ scheduler_global_number = 0x0101 ; address of thread-number-cell
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.equ scheduler_global_maxnum = 0x0004 ; maximal number of thread
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.equ scheduler_global_statu1 = 0x0102 ; address of global-status-cell 1
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.equ scheduler_global_statu2 = 0x0103 ; address of global-status-cell 2
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.equ scheduler_global_unused = 0x0104 ; start address of unused block
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.equ scheduler_global_thread = 0x010B ; starting address of scheduler memory
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.equ scheduler_global_length = 0x0026 ; length of thread in scheduler memory
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.equ scheduler_global_lastad = 0x0142 ; last address of scheduler memory
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.equ scheduler_global_stacks = 0x3FFF ; start address of stacks
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.equ scheduler_offset_stacks = 0x0080 ; length of 1 stack
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.equ scheduler_offset_instat = 0x0000 ; offset of internal sr in scheduler memory
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.equ scheduler_offset_instrh = 0x0001 ; offset of iph in scheduler memory
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.equ scheduler_offset_instrl = 0x0002 ; offset of ipl in scheduler memory
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.equ scheduler_offset_status = 0x0003 ; offset of sr in scheduler memory
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.equ scheduler_offset_stackh = 0x0004 ; offset of sph in scheduler memory
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.equ scheduler_offset_stackl = 0x0005 ; offset of spl in scheduler memory
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.equ scheduler_offset_gprsta = 0x0006 ; start offset of gpr in scheduler momory
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.equ scheduler_offset_gprend = 0x0025 ; end offset of gpr in scheduler memory
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;; scheduler memory
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;
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; We need to save the number of threads, the number of the active thread
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; and some other things.
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; For every thread we need to save:
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; - the instruction pointer (2 byte)
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; - the status register (1 byte)
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; - the stack pointer (2 byte)
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; - all 32 pgr
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; - plus 1 byte of status-values for the scheduler
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; => 38 bytes -> $26; starting at $06B
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; so: the sp of our thread x is calculated this way:
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; address = scheduler_global_thread + scheduler_global_length * x + scheduler_offset_stackp
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;
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;; scheduler memory map
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;
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; $0100 active thread
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; $0101 number of threads
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; $0102 sr1 of scheduler
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; $0103 sr2 of scheduler
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; // we still have 8 bytes of memory here
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; $010B
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; thread 0
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; $010B internal sr
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; $010C iph
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; $010D ipl
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; $010E sr
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; $010F sph
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; $0110 spl
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; $0111
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; gpr
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; $0130
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; $0130
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; $0131
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; thread 1
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; $0131 internal sr
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; $0132 iph
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; $0133 ipl
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; $0134 sr
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; $0135 sph
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; $0136 spl
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; $0137
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; gpr
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; $0156
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; $0156
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; $0157
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; thread 2
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; $0157 internal sr
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; $0158 iph
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; $0159 ipl
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; $015A sr
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; $015B sph
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; $015C spl
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; $015D
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; gpr
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; $017C
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; $017C
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; $017D
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; thread 3
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; $017D internal sr
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; $017E iph
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; $017F ipl
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; $0180 sr
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; $0181 sph
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; $0182 spl
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; $0183
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; gpr
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; $01A2
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; $01A2
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;
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;
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;; stacks
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;
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; As we should support 4 threads, we need 4 stacks.
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; For the calculation of the stack space (see global memory map) I assumed that
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; no stack will grow over 127 entries.
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; Our initial stackpointer for thread x will be calculated this way:
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; address = schedulder_global_stacks + scheduler_offset_stacks * x
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;
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;;
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SchedulerInit:
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push r16
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in r16, sreg
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push r16
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push r17
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push xl
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push xh
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; first we'll clear all scheduler memory cells
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ldi r16, 0
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ldi r17, low (scheduler_global_lastad)
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ldi xl, low (scheduler_global_active)
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ldi xh, high(scheduler_global_active)
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SchedulerInitLoop0: ; while(xl++ != r11)
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st x+, r16
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cp xl, r17 ; we can do this, because we'll never go over the low-byte
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brne SchedulerInitLoop0
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; add main-thread
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call SchedulerAddThread
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; start scheduler timer
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; we will use timer0 because we don't use all posibilities of timer2
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; some config
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ldi r16, 0b000000010 ; CTC
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out tccr0a, r16
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ldi r16, 0b000000100 ; Prescaler 256
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out tccr0b, r16
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ldi r16, 0b000000011 ; compare a: 3 x 256 ticks between interrupts
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out ocr0a r16
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ldi r16, 0b000000010 ; compare a interrupt
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pop xh
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pop xl
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pop r11
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pop r10
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out sreg, r10
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pop r10
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ret
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SchedulerInterrupt:
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call SchedulerChangeThread
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reti
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SchedulerAddThread:
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; if the number of running threads is 0:
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; the ip of the new thread should be here:
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; r9 -> low
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; r10 -> high
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; else: this routine will overwrite r9 & r10
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push r16
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push r17
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ldd r16, scheduler_global_number
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ldi r17, 0
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cp r16, r17
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brne SchedulerAddThreadAddThread
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; we have to get the ip
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pop r17
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std (scheduler_global_unused + 0), r17
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pop r17 ; r17 is former r16
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pop r10 ; high-byte
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pop r9 ; low-byte
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push r9
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push r10
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push r17
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ldd r17, (scheduler_global_unused + 0)
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push r17
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SchedulerAddThreadAddThread:
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; TODO
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SchedulerAddThreadEnd:
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pop r17
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pop r16
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ret
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SchedulerChangeThread:
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; puh, that will get hard
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; first we have to get the current instruction pointer
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push xl
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push xh
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push r16
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in r16, sreg
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ldi xl, low (scheduler_global_unused)
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ldi xh, high(scheduler_global_unused)
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st x+, r16 ; sreg is on unused[0]
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pop r16
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st x+, r16 ; r16 is on unused[1]
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pop r16
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st x+, r16 ; xh is on unused[2]
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pop r16
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st x+, r16 ; xl is on unused[3]
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st x+, r17 ; r17 is on unused[4]
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st x+, r18 ; r18 is on unused[5]
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st x+, r19 ; r19 is on unused[6]
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st x+, r20 ; r19 is on unused[7]
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pop r16 ; the later item in the stack is high
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pop r17 ; the earlier one is low
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; epic win !!!!!111
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; instruction pointer high is now in r16; low in r17
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; next we have to determine where we have to store our data
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ldd r18 scheduler_global_active
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; number of current thread is now in r18
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; now we have to determine the start address of our thread memory
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ldi xl, low (scheduler_global_thread)
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ldi xh, high(scheduler_global_thread)
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ldi r19, scheduler_global_length
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ldi r20, 0
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SchedulerChangeThreadLoop0: ; while (r20++ != r18)
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cp r20, r18
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breq SchedulerChangeThreadLoop0End
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; we can do the following, because the address can not be greater
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; than 0x00FF (as you can see in the scheduler memory map)
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add xl, r19
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inc r20
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jmp SchedulerChangeThreadLoop0
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SchedulerChangeThreadLoop0End:
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; x now contains the start address of our thread memory
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; let's copy some data
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; this is, because we don't want to modify the status register
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ld r11, x+
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; instruction pointer
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st x+, r16
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st x+, r17
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; we need the status register, it's saved in unused[0]
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ldd r16, scheduler_global_unused
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st x+, r16
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; so: the next step is the stack pointer
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in r16, sph
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st x+, r16
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in r16, spl
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st x+, r16
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; whew. next we have to save all the pgrs
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st x+, r0
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st x+, r1
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st x+, r2
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st x+, r3
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st x+, r4
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st x+, r5
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st x+, r6
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st x+, r7
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st x+, r8
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st x+, r9
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st x+, r10
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st x+, r11
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st x+, r12
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st x+, r13
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st x+, r14
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st x+, r15
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ldd r16, (scheduler_global_unused + 1)
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st x+, r16
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ldd r16, (scheduler_global_unused + 4) ; this is r17
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st x+, r16
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ldd r16, (scheduler_global_unused + 5) ; this is r18
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st x+, r16
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ldd r16, (scheduler_global_unused + 6) ; this is r19
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st x+, r16
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ldd r16, (scheduler_global_unused + 7) ; this is r20
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st x+, r16
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st x+, r21
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st x+, r22
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st x+, r23
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st x+, r24
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st x+, r25
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ldd r16, (scheduler_global_unused + 3) ; this is xl
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st x+, r16
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ldd r16, (scheduler_global_unused + 2) ; this is xh
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st x+, r16
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st x+, yl
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st x+, yh
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st x+, zl
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st x+, zh
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; soooo. we now have to get to know which is the next thread.
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; r18 contains the nr of the active thread
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; we now increment r18 (because we want the next thread)
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inc r18
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ldd r17, (scheduler_global_number)
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; r17 now containes the number of threads
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; if r17 equals r18 our calculated next thread number is too high
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cpi r17, r18
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brne SchedulerChangeThreadHop0 ; if (r17 == r18)
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ldi r18, 0
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SchedulerChangeThreadHop0:
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; so now we'll try to calculate the position of the scheduler memory
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; for thread [insert number in r18]
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ldi xl, low (scheduler_global_thread)
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ldi xh, high(scheduler_global_thread)
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ldi r19, scheduler_global_length
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ldi r20, 0
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SchedulerChangeThreadLoop1: ; while (r20++ != r18)
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cp r20, r18
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breq SchedulerChangeThreadLoop1End
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; we can do the following, because the address can not be greater
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; than 0x00FF (as you can see in the scheduler memory map)
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add xl, r19
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inc r20
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jmp SchedulerChangeThreadLoop1
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SchedulerChangeThreadLoop1End:
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ld x+, r1 ; internal sr: we don't need it
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ld x+, r2 ; iph is in r2
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ld x+, r3 ; ipl is in r3
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ld x+, r16 ; sr is in r16
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ld x+, r5 ; sph is in r5
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ld x+, r6 ; spl is in r6
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std (scheduler_global_unused + 0), r16 ; sr is in unused[0]
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; let's set the stack pointer back
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out sph r5
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out spl r6
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; let's push the instruction pointer back to the stack
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push r3 ; the earlier one is low
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push r2 ; the later one is high
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; and now all registers again
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ld r1, x+
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ld r2, x+
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ld r3, x+
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ld r4, x+
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ld r5, x+
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ld r6, x+
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ld r7, x+
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ld r8, x+
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ld r9, x+
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ld r10, x+
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ld r11, x+
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ld r12, x+
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ld r13, x+
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ld r14, x+
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ld r15, x+
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ld r16, x+
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push r16 ; r16 is now on stack
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ld r17, x+
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ld r18, x+
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ld r19, x+
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ld r20, x+
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ld r21, x+
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ld r22, x+
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ld r23, x+
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ld r24, x+
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ld r25, x+
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ld r16, x+
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std (scheduler_global_unused + 2), r16 ; xl is in unused[2]
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ld r16, x+
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std (scheduler_global_unused + 3), r16 ; xh is in unused[3]
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ld yl, x+
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ld yh, x+
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ld zl, x+
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ld zh, x+
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ldd xl, (scheduler_global_unused + 2)
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ldd xh, (scheduler_global_unused + 3)
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; finaly we just have to replace the status register
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; and we are done
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ldd r16, (scheduler_global_unused + 0)
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out sreg r16
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pop r16
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; done
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ret |