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added a few lines to snow

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Perry Kivolowitz 2022-12-10 23:30:01 -06:00
parent 96bb9755db
commit 90833b214a
1 changed files with 21 additions and 7 deletions
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28
projects/snow/main.s
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@ -17,19 +17,25 @@ main: stp x29, x30, [sp, -16]!
// Allocate the storm.
mov x0, NUM_FLAKES
mov x0, NUM_FLAKES // Calculate space needed.
mov x1, Flake.size
mul x0, x0, x1
bl malloc
cbnz x0, 1f
str x0, [sp, -16]! // Save for memset.
bl malloc // Attempt the allocation.
cbnz x0, 1f // Branch if successful.
ldr x0, =bad_malloc
add sp, sp, 16 // Undo stack change.
ldr x0, =bad_malloc // Inform user of tragedy.
bl puts
mov w0, 1
b bye
1: mov storm, x0
1: mov storm, x0 // The base address of the
// allocated memory will be
// preserved in x27.
ldr x2, [sp], 16 // Restore the allocation size.
mov w1, xzr // Fill with zero.
bl memset // x0 still had base address.
99: mov x0, storm
bl free
@ -40,8 +46,16 @@ bye: ldp x27, x28, [sp], 16
ldp x20, x30, [sp], 16
ret
/* x0 contains the address of a Flake in need of being reset.
The column number of a Flake is anywhere from 1 to 80 (a
default terminal). The starting line is anywhere from 1 to
48 (24 x 2) lines ABOVE the screen. This allows the flakes to
drift downward without apparent gaps or bunches.
*/
ResetFlake:
stp x20, x30, [sp, -16]!
ldp x20, x30, [sp], 16
ret
.data
bad_malloc: .asciz "Allocation of flakes has failed"