| 1 | //! Memory management — allocate, deallocate, string operations. |
| 2 | //! |
| 3 | //! All heap allocation goes through these functions so we can |
| 4 | //! track allocations, detect leaks, and implement Fortran's |
| 5 | //! automatic deallocation semantics. |
| 6 | |
| 7 | use std::ptr; |
| 8 | |
| 9 | // Use libc malloc/free directly so allocate/deallocate are paired correctly |
| 10 | // without needing to track Rust Layout. The system allocator on macOS returns |
| 11 | // 16-byte aligned pointers from malloc, satisfying our alignment requirement. |
| 12 | extern "C" { |
| 13 | fn malloc(size: usize) -> *mut u8; |
| 14 | fn free(ptr: *mut u8); |
| 15 | } |
| 16 | |
| 17 | /// Allocate `size` bytes on the heap. Returns a pointer. |
| 18 | /// Aborts on allocation failure (Fortran ALLOCATE with no STAT=). |
| 19 | #[no_mangle] |
| 20 | pub extern "C" fn afs_allocate(size: i64) -> *mut u8 { |
| 21 | if size <= 0 { |
| 22 | return ptr::null_mut(); |
| 23 | } |
| 24 | let ptr = unsafe { malloc(size as usize) }; |
| 25 | if ptr.is_null() { |
| 26 | eprintln!("ALLOCATE: out of memory ({} bytes)", size); |
| 27 | std::process::exit(1); |
| 28 | } |
| 29 | ptr |
| 30 | } |
| 31 | |
| 32 | /// Deallocate memory previously allocated by afs_allocate. |
| 33 | #[no_mangle] |
| 34 | pub extern "C" fn afs_deallocate(ptr: *mut u8) { |
| 35 | if ptr.is_null() { |
| 36 | return; |
| 37 | } |
| 38 | unsafe { free(ptr) }; |
| 39 | } |
| 40 | |
| 41 | /// Concatenate two strings. Returns a newly allocated string. |
| 42 | /// Caller is responsible for freeing the result. |
| 43 | #[no_mangle] |
| 44 | pub extern "C" fn afs_string_concat(a: *const u8, alen: i64, b: *const u8, blen: i64) -> *mut u8 { |
| 45 | let total = (alen + blen) as usize; |
| 46 | let result = afs_allocate(total as i64); |
| 47 | if !a.is_null() && alen > 0 { |
| 48 | unsafe { ptr::copy_nonoverlapping(a, result, alen as usize) }; |
| 49 | } |
| 50 | if !b.is_null() && blen > 0 { |
| 51 | unsafe { ptr::copy_nonoverlapping(b, result.add(alen as usize), blen as usize) }; |
| 52 | } |
| 53 | result |
| 54 | } |
| 55 | |
| 56 | /// Copy a string into a fixed-length buffer, padding with spaces. |
| 57 | /// Used for character assignment to fixed-length variables. |
| 58 | #[no_mangle] |
| 59 | pub extern "C" fn afs_string_copy(dest: *mut u8, dest_len: i64, src: *const u8, src_len: i64) { |
| 60 | if dest.is_null() || dest_len <= 0 { |
| 61 | return; |
| 62 | } |
| 63 | let copy_len = std::cmp::min(src_len, dest_len) as usize; |
| 64 | if !src.is_null() && copy_len > 0 { |
| 65 | unsafe { ptr::copy_nonoverlapping(src, dest, copy_len) }; |
| 66 | } |
| 67 | // Pad remainder with spaces (Fortran character assignment rule). |
| 68 | if (copy_len as i64) < dest_len { |
| 69 | unsafe { |
| 70 | ptr::write_bytes(dest.add(copy_len), b' ', (dest_len as usize) - copy_len); |
| 71 | } |
| 72 | } |
| 73 | } |
| 74 | |
| 75 | /// Compare two strings lexicographically. |
| 76 | /// Returns negative, zero, or positive (like strcmp but for counted strings). |
| 77 | #[no_mangle] |
| 78 | pub extern "C" fn afs_string_compare(a: *const u8, alen: i64, b: *const u8, blen: i64) -> i32 { |
| 79 | let sa = if !a.is_null() && alen > 0 { |
| 80 | unsafe { std::slice::from_raw_parts(a, alen as usize) } |
| 81 | } else { |
| 82 | &[] |
| 83 | }; |
| 84 | let sb = if !b.is_null() && blen > 0 { |
| 85 | unsafe { std::slice::from_raw_parts(b, blen as usize) } |
| 86 | } else { |
| 87 | &[] |
| 88 | }; |
| 89 | sa.cmp(sb) as i32 |
| 90 | } |
| 91 |