diff options
Diffstat (limited to 'contrib/loaders/checksum')
| -rw-r--r-- | contrib/loaders/checksum/armv7m_crc.s | 37 |
1 files changed, 21 insertions, 16 deletions
diff --git a/contrib/loaders/checksum/armv7m_crc.s b/contrib/loaders/checksum/armv7m_crc.s index 4a1e8b4a..8dfc40ad 100644 --- a/contrib/loaders/checksum/armv7m_crc.s +++ b/contrib/loaders/checksum/armv7m_crc.s @@ -26,41 +26,46 @@ .text .syntax unified - .arch armv7-m + .cpu cortex-m0 .thumb .thumb_func - + .align 2 _start: -main: +main: mov r2, r0 - mov r0, #0xffffffff /* crc */ + movs r0, #0 + mvns r0, r0 + ldr r6, CRC32XOR mov r3, r1 - mov r4, #0 + movs r4, #0 b ncomp nbyte: ldrb r1, [r2, r4] - - ldr r7, CRC32XOR - eor r0, r0, r1, asl #24 - mov r5, #0 + lsls r1, r1, #24 + eors r0, r0, r1 + movs r5, #0 loop: cmp r0, #0 - mov r6, r0, asl #1 - add r5, r5, #1 - mov r0, r6 - it lt - eorlt r0, r6, r7 + bge notset + lsls r0, r0, #1 + eors r0, r0, r6 + b cont +notset: + lsls r0, r0, #1 +cont: + adds r5, r5, #1 cmp r5, #8 bne loop - - add r4, r4, #1 + adds r4, r4, #1 ncomp: cmp r4, r3 bne nbyte bkpt #0 + .align 2 + CRC32XOR: .word 0x04c11db7 .end |