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Added more helpers for memory ptr math

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This commit is contained in:
Edward R. Gonzalez 2024-03-05 10:16:50 -05:00
parent d83d1cc128
commit 218af644d6
1 changed files with 50 additions and 17 deletions
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67
code/grime_memory.odin
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@ -20,6 +20,43 @@ terabytes :: #force_inline proc "contextless" ( tb : $ integer_type ) -> intege
return tb * Terabyte
}
// See: core/mem.odin, I wanted to study it an didn't like the naming.
@(require_results)
calc_padding_with_header :: proc "contextless" (pointer: uintptr, alignment: uintptr, header_size: int) -> int
{
alignment_offset := pointer & (alignment - 1)
initial_padding := uintptr(0)
if alignment_offset != 0 {
initial_padding = alignment - alignment_offset
}
header_space_adjustment := uintptr(header_size)
if initial_padding < header_space_adjustment
{
additional_space_needed := header_space_adjustment - initial_padding
unaligned_extra_space := additional_space_needed & (alignment - 1)
if unaligned_extra_space > 0 {
initial_padding += alignment * (1 + (additional_space_needed / alignment))
}
else {
initial_padding += alignment * (additional_space_needed / alignment)
}
}
return int(initial_padding)
}
// Helper to get the the beginning of memory after a slice
memory_after :: proc( slice : []byte ) -> ( ^ byte) {
return ptr_offset( & slice[0], len(slice) )
}
memory_after_header :: proc( header : ^($ Type) ) -> ( [^]byte) {
return cast( [^]byte) (cast( [^]Type) header)[ 1:]
}
// Initialize a sub-section of our virtual memory as a sub-arena
sub_arena_init :: proc( address : ^ byte, size : int ) -> ( ^ Arena) {
Arena :: mem.Arena
@ -31,10 +68,6 @@ sub_arena_init :: proc( address : ^ byte, size : int ) -> ( ^ Arena) {
return sub_arena
}
// Helper to get the the beginning of memory after a slice
memory_after :: proc( slice : []byte ) -> ( ^ byte) {
return ptr_offset( & slice[0], len(slice) )
}
// Since this is a prototype, all memory is always tracked. No arena is is interfaced directly.
TrackedAllocator :: struct {
@ -77,6 +110,19 @@ tracked_allocator_init :: proc( size, internals_size : int, allocator := context
return result
}
arena_allocator_init_vmem :: proc( vmem : [] byte ) -> ^ Arena
{
arena_size :: size_of( Arena)
backing_size := len(vmem)
result := cast( ^ Arena) & vmem[0]
result_slice := slice_ptr( & vmem[0], arena_size )
backing_slice := slice_ptr( memory_after( result_slice), backing_size )
arena_init( result, backing_slice )
return result
}
tracked_allocator_init_vmem :: proc( vmem : [] byte, internals_size : int ) -> ^ TrackedAllocator
{
arena_size :: size_of( Arena)
@ -99,16 +145,3 @@ tracked_allocator_init_vmem :: proc( vmem : [] byte, internals_size : int ) -> ^
tracking_allocator_init( & result.tracker, arena_allocator( backing ), arena_allocator( internals ) )
return result
}
arena_allocator_init_vmem :: proc( vmem : [] byte ) -> ^ Arena
{
arena_size :: size_of( Arena)
backing_size := len(vmem)
result := cast( ^ Arena) & vmem[0]
result_slice := slice_ptr( & vmem[0], arena_size )
backing_slice := slice_ptr( memory_after( result_slice), backing_size )
arena_init( result, backing_slice )
return result
}