xtask/starfive/visionfive2: simplify header creation

Signed-off-by: Daniel Maslowski <info@orangecms.org>

xtask/src/starfive/visionfive2_hdr.rs

@@ -1,3 +1,6 @@
+const CRC_IV: u32 = 0xffff_ffff;
+const CRC_SV: u32 = 0x04c1_1db7;
+
 // It is not clear what CRC starfive had in mind, they wrote their own ...
 fn crc32_reverse(x: u32) -> u32 {
     let mut x = x;
@@ -20,40 +23,31 @@ fn crc32(iv: u32, sv: u32, data: Vec<u8>) -> u32 {
             byte <<= 1;
         }
     }
-
-    crc
-}
-
-fn crc32_final(iv: u32) -> u32 {
-    crc32_reverse(iv ^ !0u32)
+    crc32_reverse(crc ^ iv)
 }
 
-/* version: shall be 0x01010101
- * (from https://doc-en.rvspace.org/VisionFive2/SWTRM/VisionFive2_SW_TRM/create_spl.html) */
-const VERSION: u32 = 0x0101_0101;
-// Offset of backup SBL from Flash info start (from input_sbl_normal.cfg)
-const BACKUP: u32 = 0x20_0000;
 // offset of spl header: 64+256+256 = 0x240
 const HEADER_OFFSET: u32 = 0x0240;
+const HEADER_OFFSET_BYTES: [u8; 4] = HEADER_OFFSET.to_le_bytes();
+// Offset of backup SBL from Flash info start (from input_sbl_normal.cfg)
+const BACKUP_OFFSET: u32 = 0x20_0000;
+const BACKUP_OFFSET_BYTES: [u8; 4] = BACKUP_OFFSET.to_le_bytes();
 /* Offset from HDR to SPL_IMAGE, 0x400 (00 04 00 00) currently */
 const HEADER_SIZE: u32 = 0x0400;
+const HEADER_SIZE_BYTES: [u8; 4] = HEADER_SIZE.to_le_bytes();
+
+/* this is a shortcut */
+const VERSION_OFFSET: usize = HEADER_OFFSET + 0x0044;
 
-const CRC_IV: u32 = !0;
-const CRC_SV: u32 = 0x04c11db7;
+/* version: shall be 0x01010101
+ * (from https://doc-en.rvspace.org/VisionFive2/SWTRM/VisionFive2_SW_TRM/create_spl.html) */
+const VERSION: u32 = 0x0101_0101;
+const VERSION_BYTES: [u8; 4] = VERSION.to_le_bytes();
 
-// The use of a packed struct is kind of pointless. Just emit the proper things in the proper order.
+// The use of a packed struct is kind of pointless.
+// Just emit the proper things in the proper order.
 // Push them into the output.
 // Also, let's get real: there are no big-endian machines left. Assume LE.
-//        uint32_t sofs;          /* offset of spl header: 64+256+256 = 0x240 */
-//        uint32_t bofs;          /* SBL_BAK_OFFSET: Offset of backup SBL from Flash info start (from input_sbl_normal.cfg) */
-//        uint8_t  zro2[636];
-//        uint32_t vers;          /* version: shall be 0x01010101
-//                                 * (from https://doc-en.rvspace.org/VisionFive2/SWTRM/VisionFive2_SW_TRM/create_spl.html) */
-//        uint32_t fsiz;          /* u-boot-spl.bin size in bytes */
-//        uint32_t res1;          /* Offset from HDR to SPL_IMAGE, 0x400 (00 04 00 00) currently */
-//        uint32_t crcs;          /* CRC32 of u-boot-spl.bin */
-//        uint8_t  zro3[364];
-
 pub fn spl_create_hdr(dat: Vec<u8>) -> Vec<u8> {
     /*
         // need to find out which one to use, but it's not this one.
@@ -65,40 +59,20 @@ pub fn spl_create_hdr(dat: Vec<u8>) -> Vec<u8> {
     }
     */
     let v = crc32(CRC_IV, CRC_SV, dat.clone());
-    let fv = crc32_final(v);
-
-    let mut hdr = vec![];
-
-    let spl_header_offset: [u8; 4] = HEADER_OFFSET.to_le_bytes();
-    hdr.extend_from_slice(&spl_header_offset);
-
-    let backup: [u8; 4] = BACKUP.to_le_bytes();
-    hdr.extend_from_slice(&backup);
-
-    hdr.resize(hdr.len() + 636, 0);
-
-    let version: [u8; 4] = VERSION.to_le_bytes();
-    hdr.extend_from_slice(&version);
-
+    let checksum: [u8; 4] = v.to_le_bytes();
     let data_len: [u8; 4] = (dat.len() as u32).to_le_bytes();
-    hdr.extend_from_slice(&data_len); /* u-boot-spl.bin size in bytes */
-
-    println!("boot blob size: {}", dat.len());
 
-    let data_offset: [u8; 4] = HEADER_SIZE.to_le_bytes();
-    hdr.extend_from_slice(&data_offset);
-
-    /* CRC32 of dat */
-    let l: [u8; 4] = fv.to_le_bytes();
-    hdr.extend_from_slice(&l);
-    // fill up to HEADER_SIZE
-    hdr.resize(hdr.len() + 364, 0);
-
-    assert!(
-        hdr.len() == HEADER_SIZE as usize,
-        "hdr is {:x} bytes, not {HEADER_SIZE}",
-        hdr.len()
-    );
+    let mut hdr = vec![];
+    hdr.extend_from_slice(&HEADER_OFFSET_BYTES);
+    hdr.extend_from_slice(&BACKUP_OFFSET_BYTES);
+    hdr.resize(HEADER_OFFSET as usize, 0);
+    // NOTE: there are apparently other optional fields, unused here as of now
+    hdr.resize(VERSION_OFFSET, 0);
+    hdr.extend_from_slice(&VERSION_BYTES);
+    hdr.extend_from_slice(&data_len);
+    hdr.extend_from_slice(&HEADER_SIZE_BYTES);
+    hdr.extend_from_slice(&checksum);
+    hdr.resize(HEADER_SIZE as usize, 0);
     hdr.extend(&dat);
     hdr
 }