happz/ducky

#include "arch/ducky.h"
#include "arch/rtc.h"
#include "arch/svga.h"

#define FG     0x0400

#define INSERT_DOT \
  li r1, 46        \
  stb r0, r1       \
  inc r0

#define INSERT_SPACE \
  li r1, 32          \
  stb r0, r1         \
  inc r0

#define INSERT_COLON \
  li r1, 58          \
  stb r0, r1         \
  inc r0

#define INSERT_CHR(_chr) \
  li r1, _chr            \
  stb r0, r1             \
  inc r0

#define INSERT_DIGITS(_reg) \
  mov r1, _reg              \
  call print_digits


  .data

  .type stack, space, 64
  .type iteration, word, 50
  .type second, byte, 255


  .text

main:
  li r0, RTC_MMIO_ADDRESS
  add r0, RTC_MMIO_FREQ
  li r1, 5
  stb r0, r1

  // interrupts are disabled, there are no interrupt routines
  li r0, 0x00
  la r1, irq_routine
  stw r0, r1
  add r0, INT_SIZE
  la r1, stack
  add r1, 64
  stw r0, r1

  // OK, we're ready, enable interrupts and elts go
  sti

.loop:
  idle
  j .loop
  hlt 0x00


  //
  // void print_digits(void *buff, int n)
  //

print_digits:
  push r2
  mov r2, r1

  div r1, 10
  mod r2, 10
  add r1, 48
  add r2, 48

  stb r0, r1
  inc r0
  stb r0, r2
  inc r0

  pop r2

  ret

irq_routine:
  li r10, RTC_MMIO_ADDRESS
  add r10, RTC_MMIO_SECOND
  lb r9, r10

  li r10, RTC_MMIO_ADDRESS
  add r10, RTC_MMIO_MINUTE
  lb r8, r10

  li r10, RTC_MMIO_ADDRESS
  add r10, RTC_MMIO_HOUR
  lb r7, r10

  li r10, RTC_MMIO_ADDRESS
  add r10, RTC_MMIO_DAY
  lb r6, r10

  li r10, RTC_MMIO_ADDRESS
  add r10, RTC_MMIO_MONTH
  lb r5, r10

  li r10, RTC_MMIO_ADDRESS
  add r10, RTC_MMIO_YEAR
  lb r4, r10

  li r0, second
  lb r0, r0
  cmp r0, r9
  be __quit

__redraw:
  // save new value
  li r0, second
  stb r0, r9

  // frame buffer address
  li r10, 0xA000

  // update frame buffer
  mov r0, r10
  add r0, 16
  li r1, 0x00

  // clear frame buffer
__memreset_loop:
  stb r0, r1
  dec r0
  cmp r0, r10
  bne __memreset_loop

  // write new values
  mov r0, r10

  INSERT_DIGITS(r6) // day
  INSERT_DOT
  INSERT_SPACE
  INSERT_DIGITS(r5) // month
  INSERT_DOT
  INSERT_SPACE
  INSERT_CHR(50)    // century
  INSERT_CHR(48)
  INSERT_DIGITS(r4) // year
  INSERT_SPACE
  INSERT_DIGITS(r7) // hours
  INSERT_COLON
  INSERT_DIGITS(r8) // minutes
  INSERT_COLON
  INSERT_DIGITS(r9) // seconds

  // refresh screen
  li r0, VGA_MMIO_ADDRESS
  add r0, VGA_MMIO_COMMAND
  li r1, VGA_CMD_REFRESH
  sts r0, r1

__quit:
  la r0, iteration
  lw r1, r0
  dec r1
  bz __halt
  stw r0, r1

  retint

__halt:
  hlt 0x00