diff options
Diffstat (limited to 'tools')
| -rwxr-xr-x | tools/mpy_ld.py | 22 |
1 files changed, 19 insertions, 3 deletions
diff --git a/tools/mpy_ld.py b/tools/mpy_ld.py index 45aadadd5..c77c46d44 100755 --- a/tools/mpy_ld.py +++ b/tools/mpy_ld.py @@ -89,10 +89,26 @@ def asm_jump_x86(entry): def asm_jump_thumb(entry): - # Only signed values that fit in 12 bits are supported + # This function must return the same number of bytes for the encoding of the jump + # regardless of the value of `entry`. b_off = entry - 4 - assert b_off >> 11 == 0 or b_off >> 11 == -1, b_off - return struct.pack("<H", 0xE000 | (b_off >> 1 & 0x07FF)) + if b_off >> 11 == 0 or b_off >> 11 == -1: + # Signed value fits in 12 bits. + b0 = 0xE000 | (b_off >> 1 & 0x07FF) + b1 = 0 + b2 = 0 + b3 = 0 + else: + # Use bl to do a large jump/call: + # push {r0, lr} + # bl <dest> + # pop {r0, pc} + b_off -= 2 # skip "push {r0, lr}" + b0 = 0xB400 | 0x0100 | 0x0001 # push, lr, r0 + b1 = 0xF000 | (((b_off) >> 12) & 0x07FF) + b2 = 0xF800 | (((b_off) >> 1) & 0x07FF) + b3 = 0xBC00 | 0x0100 | 0x0001 # pop, pc, r0 + return struct.pack("<HHHH", b0, b1, b2, b3) def asm_jump_thumb2(entry): |