;; BEGIN BOOTSTRAP

@use ext_std:*

@let sp              RH   ; stack pointer (points to empty slot at top of stack)
@let fp              RG   ; frame pointer (points to base of currently active frame)

@let vector_table    0x10
@let vt_ISR0         0x10 ; ISR0
@let vt_ISR1         0x11 ; ISR1
@let vt_ISR2         0x12 ; ISR2
@let vt_ISR3         0x13 ; ISR3
@let vt_stack_addr   0x14 ; Stack address
@let vt_term_pp_addr 0x15 ; Terminal peripheral address
@let vt_kb_pp_addr   0x16 ; Keyboard peripheral address
@let vt_gr_mode_addr 0x17 ; Graphics mode setting address
@let vt_sprite_mem   0x18 ; Sprite memory address
@let vt_text_mem     0x19 ; Text memory buffer address

@let stack_segment   0x8000
@let mmio_segment    0xE7F0
@let terminal_addr   0xE7F0
@let keyboard_addr   0xE7F1
@let gr_mode_addr    0xE7F2
@let sprite_mem      0xE800
@let text_mem        0xF800

@let gr_disabled_mode 0b00
@let gr_text_mode     0b01
@let gr_sprite_mode   0b10

@address 0x0
  ldi vt_stack_addr RA
  ldr RA SP
  mov SP FP
  jpi program_segment

@address vector_table
  keyboard_isr   ; 0x10
  hlt_isr        ; 0x11
  hlt_isr        ; 0x12
  hlt_isr        ; 0x13
  stack_segment  ; 0x14
  terminal_addr  ; 0x15
  keyboard_addr  ; 0x16
  gr_mode_addr   ; 0x17
  sprite_mem     ; 0x18
  text_mem       ; 0x19

@label hlt_isr
  ldi 0x55 RE
  hlt

@label keyboard_isr
  spu RA
  spu RB
  ldi vt_kb_pp_addr RA
  ldr RA RA
  ldr RA RA
  ldi vt_term_pp_addr RB
  ldr RB RB
  str RA RB
  spo RB
  spo RA
  rti

@label program_segment
  ldi vt_gr_mode_addr RA
  ldr RA RA
  ldi gr_disabled_mode RB
  str RB RA

  jpi main

;; END BOOTSTRAP

@label text_mode
  1
@label graphics_mode_addr_p
  23
@label text_mem_addr_p
  25
@label int_0
  65
@label int_6
  26

; <ast.FunctionDef object at 0x104969570>
@label nth_letter
; stack frame with offsets
; n 0
; <ast.Return object at 0x1049694b0>
; <ast.Add object at 0x104686bf0>
; BinOp lhs <ast.BinOp object at 0x104969480>
; <ast.Call object at 0x104969450>
; Builtin call ord [<ast.Constant object at 0x1049693c0>]
; <ast.Constant object at 0x1049693c0>
  ldi int_0 RC
  ldr RC RC ; int_0 = 65
  spu RC
; BinOp rhs <ast.BinOp object at 0x104969480>
; <ast.Name object at 0x104969390> (n)
  ldi 0 RC
  add FP RC RC
  ldr RC RC
  spu RC
  spo RD
  spo RC
  add RC RD RC
  spu RC
; return value is on top of stack
; return from function
  subi FP 1 FP
  ldr FP RB
  jpr RB

@label main
; stack frame with offsets
; graphics_mode_addr 0
; text_mem_addr 1
; i 2
  addi SP 3 SP
; <ast.Assign object at 0x1049698d0>
; assigning graphics_mode_addr at FP + 0
; evaluating value to be assigned
; <ast.Call object at 0x104969870>
; Builtin call load [<ast.Name object at 0x1049697e0>]
; <ast.Name object at 0x1049697e0> (GRAPHICS_MODE_ADDR_P)
  ldi graphics_mode_addr_p RC
  ldr RC RC
  spu RC
; (load) dereferencing top of stack
  spo RC
  ldr RC RC
  spu RC
; assigning stack address (FP + 0) := top of stack
  spo RA
  ldi 0 RB
  add RB FP RB
  str RA RB
; <ast.Assign object at 0x1049697b0>
; assigning text_mem_addr at FP + 1
; evaluating value to be assigned
; <ast.Call object at 0x104969750>
; Builtin call load [<ast.Name object at 0x1049696c0>]
; <ast.Name object at 0x1049696c0> (TEXT_MEM_ADDR_P)
  ldi text_mem_addr_p RC
  ldr RC RC
  spu RC
; (load) dereferencing top of stack
  spo RC
  ldr RC RC
  spu RC
; assigning stack address (FP + 1) := top of stack
  spo RA
  ldi 1 RB
  add RB FP RB
  str RA RB
; <ast.Call object at 0x104969660>
; Builtin call store [<ast.Name object at 0x1049695d0>, <ast.Name object at 0x1049695a0>]
; <ast.Name object at 0x1049695d0> (graphics_mode_addr)
  ldi 0 RA
  add FP RA RA
  ldr RA RA
  spu RA
; <ast.Name object at 0x1049695a0> (TEXT_MODE)
  ldi text_mode RA
  ldr RA RA
  spu RA
  spo RB
  spo RA
  str RB RA
  ldi 0 RA
  spu RA
; popping free-standing Expr result from stack
  spo RA
; <ast.Assign object at 0x104969330>
; assigning i at FP + 2
; evaluating value to be assigned
; <ast.Constant object at 0x1049692d0>
  ldi 0 RC
  spu RC
; assigning stack address (FP + 2) := top of stack
  spo RA
  ldi 2 RB
  add RB FP RB
  str RA RB
; <ast.While object at 0x1049692a0>
@label while_test_1
; <ast.Compare object at 0x104969270>
; <ast.Name object at 0x104969240> (i)
  ldi 2 RB
  add FP RB RB
  ldr RB RB
  spu RB
; <ast.Constant object at 0x104969210>
  ldi int_6 RB
  ldr RB RB ; int_6 = 26
  spu RB
; Comparing <ast.Name object at 0x104969240> <ast.Lt object at 0x104686440> <ast.Constant object at 0x104969210>
  spo RC
  spo RB
  sub RB RC RB
  bri carry Compare_true_4
  ldi 0 RB
  spu RB
  jpi Compare_end_5
@label compare_true_4
  ldi 1 RB
  spu RB
@label compare_end_5
  spo RA
  addi RA 0 RA
  bri zero While_else_2
; <ast.Call object at 0x1049691b0>
; Builtin call store [<ast.BinOp object at 0x104969120>, <ast.Call object at 0x104969090>]
; <ast.Add object at 0x104686bf0>
; BinOp lhs <ast.BinOp object at 0x104969120>
; <ast.Name object at 0x1049690f0> (text_mem_addr)
  ldi 1 RA
  add FP RA RA
  ldr RA RA
  spu RA
; BinOp rhs <ast.BinOp object at 0x104969120>
; <ast.Name object at 0x1049690c0> (i)
  ldi 2 RA
  add FP RA RA
  ldr RA RA
  spu RA
  spo RB
  spo RA
  add RA RB RA
  spu RA
; <ast.Call object at 0x104969090>
; Call function nth_letter
  spu FP
  ldi 0 RA
  spu RA
; <ast.Name object at 0x104969030> (i)
  ldi 2 RA
  add FP RA RA
  ldr RA RA
  spu RA
  subi SP 2 FP
; set up return address and jump to subroutine
  lpc RA
  addi RA 4 RA
  str RA FP
  addi FP 1 FP
  jpi nth_letter
  spo RA
  mov FP SP
  spo FP
  spu RA
  spo RB
  spo RA
  str RB RA
  ldi 0 RA
  spu RA
; popping free-standing Expr result from stack
  spo RA
; <ast.Assign object at 0x104968580>
; assigning i at FP + 2
; evaluating value to be assigned
; <ast.Add object at 0x104686bf0>
; BinOp lhs <ast.BinOp object at 0x104968550>
; <ast.Name object at 0x104968fd0> (i)
  ldi 2 RC
  add FP RC RC
  ldr RC RC
  spu RC
; BinOp rhs <ast.BinOp object at 0x104968550>
; <ast.Constant object at 0x104968fa0>
  ldi 1 RC
  spu RC
  spo RD
  spo RC
  add RC RD RC
  spu RC
; assigning stack address (FP + 2) := top of stack
  spo RA
  ldi 2 RB
  add RB FP RB
  str RA RB
  jpi While_test_1
@label while_else_2
@label while_end_3
; <ast.While object at 0x104968f70>
@label while_test_7
; <ast.Constant object at 0x104968f40>
  ldi 1 RB
  spu RB
  spo RA
  addi RA 0 RA
  bri zero While_else_8
; <ast.Pass object at 0x104968f10>
  jpi While_test_7
@label while_else_8
@label while_end_9
  mov FP SP
  hlt