Added ELF structures for reading ELF files.

risc_v/src/elf.rs

@@ -0,0 +1,60 @@
+// elf.rs
+// Routines for reading and parsing ELF
+// (Executable and Linkable Format) files.
+// 26-April-2020
+// Stephen Marz
+
+
+// Every ELF file starts with ELF "magic", which is a sequence of four bytes 0x7f followed by capital ELF, which is 0x45, 0x4c, and 0x46 respectively.
+pub const MAGIC: u32 = 0x464c_457f;
+
+/// The ELF header contains information about placement and numbers of the important sections within our file.
+#[repr(C)]
+pub struct Header {
+    pub magic: u32,
+    pub bitsize: u8,
+    pub endian: u8,
+    pub ident_abi_version: u8,
+    pub target_platform: u8,
+    pub abi_version: u8,
+    pub padding: [u8; 7],
+    pub obj_type: u16,
+    pub machine: u16, // 0xf3 for RISC-V
+    pub version: u32,
+    pub entry_addr: usize,
+    pub phoff: usize,
+    pub shoff: usize,
+    pub flags: u32,
+    pub ehsize: u16,
+    pub phentsize: u16,
+    pub phnum: u16,
+    pub shentsize: u16,
+    pub shnum: u16,
+    pub shstrndx: u16,
+}
+
+#[repr(C)]
+pub struct ProgramHeader {
+    pub seg_type: u32,
+    pub flags: u32,
+    pub off: usize,
+    pub vaddr: usize,
+    pub paddr: usize,
+    pub filesz: usize,
+    pub memsz: usize,
+    pub align: usize,
+}
+
+pub const TYPE_EXEC: u16 = 2;
+
+pub const PROG_READ: u8 = 4;
+pub const PROG_WRITE: u8 = 2;
+pub const PROG_EXECUTE: u8 = 1;
+
+pub const MACHINE_RISCV: u16 = 0xf3;
+pub const PH_SEG_TYPE_NULL: u32 = 0;
+pub const PH_SEG_TYPE_LOAD: u32 = 1;
+pub const PH_SEG_TYPE_DYNAMIC: u32 = 2;
+pub const PH_SEG_TYPE_INTERP: u32 = 3;
+pub const PH_SEG_TYPE_NOTE: u32 = 4;
+