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@ .section .iwram,"ax",%progbits
.text
.align 4
.code 32

sp_store: .space 4

.type clear_screen_asm,function
.global clear_screen_asm
clear_screen_asm:
  @ r0 contains the address of the screen to clear
  @ push all registers, store stack pointer in ram
  stmfd  sp!, {r4-r12,lr}
  ldr    r1,=sp_store
  str    sp,[r1]
  @ mov    r0,r1  @ address of screen
  @ now store 0 in registers r0-r14
  mov    r1,#0
  mov    r2,#0
  mov    r3,#0
  mov    r4,#0
  mov    r5,#0
  mov    r6,#0
  mov    r7,#0
  mov    r8,#0
  mov    r9,#0
  mov    r10,#0
  mov    r11,#0
  mov    r12,#0
  mov    r13,#0
  mov    r14,#0
  @ need to clear (SCREEN_TILE_HEIGHT*SCREEN_TILE_WIDTH * 8*8) / (2*4)
  @ = 24*32*8*8/8 = 20*32*8 = 6144 "counts"
  @ 6144 / 14 = 438  (438*14 = 6132)
  .rept 438 
  stmia  r0!, {r1-r14}
  .endr
  @ the last 12 words
  stmia  r0!, {r1-r12}
  @ get all the regs back again
  ldr    r0,=sp_store
  ldr    sp,[r0]
  ldmfd  sp!,{r4-r12,lr}
  bx     lr

.global clear_lollipop_asm
.type clear_lollipop_asm,function

clear_lollipop_asm:
  @ clear 32 words for the lollipop
  @ r0 contains address
  stmfd  sp!, {r4-r12}
  mov    r1,#0
  mov    r2,#0
  mov    r3,#0
  mov    r4,#0
  mov    r5,#0
  mov    r6,#0
  mov    r7,#0
  mov    r8,#0
  mov    r9,#0
  mov    r10,#0
  mov    r11,#0
  mov    r12,#0
  stmia  r0!, {r1-r12}  @ 12
  stmia  r0!, {r1-r12}  @ 24
  stmia  r0!, {r1-r8}   @ 32
  ldmfd  sp!, {r4-r12}
  bx     lr


.pool