WORKING ASM FUNCTION CALLS

src/compiler/elf.rs

@@ -0,0 +1,102 @@
+#[repr(C)]
+pub struct ELF64Header {
+    magic: u32,
+    class: u8,
+    endianness: u8,
+    ei_version: u8,
+    os_abi: u8,
+    os_abi_ver: u8,
+    pad: [u8; 7],
+    ty: u16,
+    machine: u16,
+    e_version: u32,
+    entry: u64,
+    program_header_offset: u64,
+    section_header_offset: u64,
+    flags: u32,
+    header_size: u16,
+    program_header_entry_size: u16,
+    program_header_num: u16,
+    section_header_entry_size: u16,
+    section_header_num: u16,
+    section_header_str_idx: u16,
+}
+
+#[repr(C)]
+pub struct ProgramHeader {
+    ty: u32,
+    flags: u32,
+    offset: u64,
+    vaddr: u64,
+    paddr: u64,
+    filesz: u64,
+    memsz: u64,
+    align: u64,
+}
+
+#[repr(C)]
+pub struct SectionHeader {
+    name_idx: u32,
+    ty: u32,
+    flags: u64,
+    addr: u64,
+    offset: u64,
+    size: u64,
+    link: u32,
+    info: u32,
+    addr_align: u64,
+    entry_size: u64,
+}
+
+// this is currently specialized for riscv64; obviously add params later
+pub fn create(program: Vec<u8>, start_offset: u64) -> Vec<u8> {
+    let addr_start = 0x1000;
+    let page_size = 0x1000;
+    let progam_size = std::mem::size_of_val(&program[..]) as u64;
+    let program_header = ProgramHeader {
+        ty: 0x1,      // LOAD
+        flags: 0b101, // executable, readable
+        offset: 0x0,
+        vaddr: addr_start,
+        paddr: addr_start,
+        filesz: progam_size,
+        memsz: progam_size,
+        align: page_size,
+    };
+    let header_len = (size_of::<ELF64Header>() + size_of::<ProgramHeader>()) as u64;
+    let program_pos = header_len;
+    let header = ELF64Header {
+        magic: 0x7f_45_4c_46u32.swap_bytes(),
+        class: 0x2,      // 64 bit
+        endianness: 0x1, // little endian
+        ei_version: 0x1,
+        os_abi: 0x0, // system-v
+        os_abi_ver: 0x0,
+        pad: [0x0; 7],
+        ty: 0x2,       // executable
+        machine: 0xf3, // risc-v
+        e_version: 0x1,
+        entry: addr_start + program_pos + start_offset,
+        program_header_offset: size_of::<ELF64Header>() as u64,
+        section_header_offset: 0x0,
+        // C ABI (16 bit instruction align) + double precision floats
+        flags: 0x1 | 0x4,
+        header_size: size_of::<ELF64Header>() as u16,
+        program_header_entry_size: size_of::<ProgramHeader>() as u16,
+        program_header_num: 0x1,
+        section_header_entry_size: size_of::<SectionHeader>() as u16,
+        section_header_num: 0x0,
+        section_header_str_idx: 0x0,
+    };
+    let mut bytes: Vec<u8> = Vec::new();
+    unsafe {
+        bytes.extend(as_u8_slice(&header));
+        bytes.extend(as_u8_slice(&program_header));
+        bytes.extend(program);
+    }
+    bytes
+}
+
+unsafe fn as_u8_slice<T: Sized>(p: &T) -> &[u8] {
+    core::slice::from_raw_parts((p as *const T) as *const u8, size_of::<T>())
+}