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particle.s
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particle.s
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.ifndef PARTICLE_S
PARTICLE_S:
.include "./time.s"
.include "./star.s"
.include "./util.s"
.include "./fixed_point.s"
.equ MAX_PARTICLES, 256
/* struct ParticleState */
.equ PS_TIMESTAMP, 0 // u32
.equ PS_COLOR, PS_TIMESTAMP + 4 // u32
.equ PS_POS_X, PS_COLOR + 4 // u64
.equ PS_POS_Y, PS_POS_X + 8 // u64
.equ PS_SIZE, PS_POS_Y + 8 // u64
.equ PS_PHASE, PS_SIZE + 8 // u64 (Q32)
.equ STRUCT_PS_SIZE, PS_PHASE + 8
/* struct ParticleManager */
.equ PM_PARTICLE_ARRAY, 0 // struct ParticleState[MAX_PARTICLES]
.equ PM_PARTICLE_COUNT, PM_PARTICLE_ARRAY + (STRUCT_PS_SIZE * MAX_PARTICLES) // u64 in [0..MAX_PARTICLES]
.equ STRUCT_PM_SIZE, PM_PARTICLE_COUNT + 8
/*
* Params:
* x0: out struct ParticleManager*
*/
particle_manager_init:
stp lr, x19, [sp, -16]!
str xzr, [x0, PM_PARTICLE_COUNT]
ldp lr, x19, [sp], 16
ret
/*
* Params:
* x0: in/out struct ParticleManager*
* x1: u64 <- x coordinate
* x2: u64 <- y coordinate
* x3: u64 <- size
* w4: u32 <- color
* x5: u64 <- phase (Q32)
*/
particle_manager_create_star:
stp lr, x19, [sp, -16]!
ldr x9, [x0, PM_PARTICLE_COUNT]
cmp x9, MAX_PARTICLES
b.ge particle_manager_create_star__end
// Calculate offset in bytes to new ParticleState
mov x10, STRUCT_PS_SIZE
mul x10, x9, x10 // x10 <- offset in bytes to new particle from beginning of array
add x10, x10, PM_PARTICLE_ARRAY // x10 <- offset in bytes to new particle from beginning of struct
add x10, x0, x10 // x10 <- &particles[particle_count]
// Increment particle count
add x9, x9, 1
str x9, [x0, PM_PARTICLE_COUNT]
str x1, [x10, PS_POS_X]
str x2, [x10, PS_POS_Y]
str x3, [x10, PS_SIZE]
str w4, [x10, PS_COLOR]
str x5, [x10, PS_PHASE]
bl get_time
str w0, [x10, PS_TIMESTAMP]
particle_manager_create_star__end:
ldp lr, x19, [sp], 16
ret
/*
* Params:
* x0: in struct ParticleManager* <- particle manager
* x1: out u32* <- framebuffer
*/
particle_manager_render:
stp lr, x19, [sp, -32]!
stp x20, x21, [sp, 16]
ldr x19, [x0, PM_PARTICLE_COUNT] // x19 <- remaining particles
add x20, x0, PM_PARTICLE_ARRAY // x20 <- pointer to current particle
mov x21, x1 // x21 <- framebuffer
particle_manager_render__next:
cmp x19, 0 // Check if any particles remain to be drawn
cbz x19, particle_manager_render__end
mov x0, x20 // x0 <- current particle*
mov x1, x21 // x1 <- framebuffer
bl particle_draw
sub x19, x19, 1 // Decrement remaining particles
add x20, x20, STRUCT_PS_SIZE // Advance pointer to next particle
b particle_manager_render__next
particle_manager_render__end:
ldp x20, x21, [sp, 16]
ldp lr, x19, [sp], 32
ret
/*
* Params:
* x0: in struct ParticleState* <- particle state
* x1: out u32* <- framebuffer
*/
particle_draw:
stp lr, x19, [sp, -32]!
stp x20, x21, [sp, 16]
mov x20, x0 // x20 <- particle state
mov x21, x1 // x21 <- framebuffer
bl get_time
lsl x0, x0, 32 // x0 <- time in us (Q32)
ldr x9, =US_PER_SECOND
udiv x0, x0, x9 // x0 <- time in seconds (Q32)
orr x1, xzr, 4 << 32 // x1 <- amplitude
orr x2, xzr, 1 << 31 // x2 <- frequency
ldr x3, [x20, PS_PHASE] // x3 <- phase
bl sine_wave_advanced
q32_to_int x9, x0, x9 // x9 <- delta size
ldr x0, [x20, PS_POS_X]
ldr x1, [x20, PS_POS_Y]
ldr x2, [x20, PS_SIZE]
add x2, x2, x9
ldr w3, [x20, PS_COLOR]
mov x4, x21
bl draw_four_point_star
ldp x20, x21, [sp, 16]
ldp lr, x19, [sp], 32
ret
.endif