103 lines
2.8 KiB
Odin
103 lines
2.8 KiB
Odin
// Relative pointer
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package relptr
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import "base:intrinsics"
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Ptr :: struct($T: typeid) {
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offset: uintptr,
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}
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Slice :: struct($T: typeid) {
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offset: uintptr,
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len: int,
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}
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SOA_Slice :: struct($T: typeid) {
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// Offset for each field of SOA struct
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offsets: [len(
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T,
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) when intrinsics.type_is_array(T) else intrinsics.type_struct_field_count(T)]uintptr,
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len: int,
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}
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from_rawptr :: #force_inline proc($T: typeid, addr: rawptr, base := context.user_ptr) -> Ptr(T) {
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offset := uintptr(addr) - uintptr(base)
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assert(offset >= 0, "ptr does not belong to this base")
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return Ptr(T){offset = offset}
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}
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from_ptr :: #force_inline proc(addr: ^$T, base := context.user_ptr) -> Ptr(T) {
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offset := uintptr(rawptr(addr)) - uintptr(base)
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assert(offset >= 0, "ptr does not belong to this base")
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return Ptr(T){offset = offset}
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}
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from_multi_ptr :: #force_inline proc(addr: [^]$T, base := context.user_ptr) -> Ptr(T) {
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offset := uintptr(rawptr(addr)) - uintptr(base)
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assert(offset >= 0, "ptr does not belong to this base")
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return Ptr(T){offset = offset}
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}
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from_slice :: #force_inline proc(slice: []$T, base := context.user_ptr) -> Slice(T) {
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offset := uintptr(rawptr(raw_data(slice))) - uintptr(base)
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assert(offset >= 0, "ptr does not belong to this base")
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return Slice(T){offset = offset, len = len(slice)}
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}
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from_soa_slice :: #force_inline proc(slice: #soa[]$T, base := context.user_ptr) -> SOA_Slice(T) {
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slice := slice
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result: SOA_Slice(T)
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FIELD_COUNT ::
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(len(T) when intrinsics.type_is_array(T) else intrinsics.type_struct_field_count(T))
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// SOA slice is just an array of pointers to each member + a footer
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src_ptrs := (transmute([^]uintptr)(&slice))[:FIELD_COUNT]
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for i in 0 ..< len(result.offsets) {
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result.offsets[i] = src_ptrs[i] - uintptr(base)
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}
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result.len = len(slice)
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return result
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}
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deref_ptr :: #force_inline proc(ptr: Ptr($T), base := context.user_ptr) -> ^T {
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return transmute(^T)(uintptr(base) + ptr.offset)
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}
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deref_multi_ptr :: #force_inline proc(ptr: Ptr($T), base := context.user_ptr) -> [^]T {
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return transmute([^]T)(uintptr(base) + ptr.offset)
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}
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deref_slice :: #force_inline proc(slice: Slice($T), base := context.user_ptr) -> []T {
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return (transmute([^]T)(uintptr(base) + slice.offset))[:slice.len]
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}
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deref_soa_slice :: #force_inline proc(slice: SOA_Slice($T), base := context.user_ptr) -> #soa[]T {
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result: #soa[]T
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footer := raw_soa_footer_slice(&result)
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FIELD_COUNT ::
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(len(T) when intrinsics.type_is_array(T) else intrinsics.type_struct_field_count(T))
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// Just in case SOA layout changes
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#assert(size_of(result) == (FIELD_COUNT * size_of(rawptr)) + size_of(footer))
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// SOA slice is just an array of pointers to each member + a footer
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result_ptrs := (transmute([^]uintptr)(&result))[:FIELD_COUNT]
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for i in 0 ..< len(slice.offsets) {
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result_ptrs[i] = uintptr(base) + slice.offsets[i]
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}
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footer.len = slice.len
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return result
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}
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