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| author | Damien George <damien.p.george@gmail.com> | 2015-02-16 18:17:07 +0000 |
|---|---|---|
| committer | Damien George <damien.p.george@gmail.com> | 2015-02-16 18:17:07 +0000 |
| commit | eff10f66a65d0577aa9d10ee08b469cb9c83e1a3 (patch) | |
| tree | 39296926928e62c117f6ad5c65401e4aff403235 /py/asmthumb.c | |
| parent | 42495392daa5efd3cb706d396f244ab7c9049b29 (diff) | |
| download | micropython-eff10f66a65d0577aa9d10ee08b469cb9c83e1a3.tar.gz micropython-eff10f66a65d0577aa9d10ee08b469cb9c83e1a3.zip | |
py: Implement bl/bx instructions for inline Thumb assembler.
Diffstat (limited to 'py/asmthumb.c')
| -rw-r--r-- | py/asmthumb.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/py/asmthumb.c b/py/asmthumb.c index 854f455455..d23be0ef2b 100644 --- a/py/asmthumb.c +++ b/py/asmthumb.c @@ -40,6 +40,7 @@ #define SIGNED_FIT8(x) (((x) & 0xffffff80) == 0) || (((x) & 0xffffff80) == 0xffffff80) #define SIGNED_FIT9(x) (((x) & 0xffffff00) == 0) || (((x) & 0xffffff00) == 0xffffff00) #define SIGNED_FIT12(x) (((x) & 0xfffff800) == 0) || (((x) & 0xfffff800) == 0xfffff800) +#define SIGNED_FIT23(x) (((x) & 0xffc00000) == 0) || (((x) & 0xffc00000) == 0xffc00000) struct _asm_thumb_t { mp_uint_t pass; @@ -455,6 +456,20 @@ void asm_thumb_bcc_label(asm_thumb_t *as, int cond, uint label) { } } +#define OP_BL_HI(byte_offset) (0xf000 | (((byte_offset) >> 12) & 0x07ff)) +#define OP_BL_LO(byte_offset) (0xf800 | (((byte_offset) >> 1) & 0x07ff)) + +void asm_thumb_bl(asm_thumb_t *as, uint label) { + mp_uint_t dest = get_label_dest(as, label); + mp_int_t rel = dest - as->code_offset; + rel -= 4; // account for instruction prefetch, PC is 4 bytes ahead of this instruction + if (SIGNED_FIT23(rel)) { + asm_thumb_op32(as, OP_BL_HI(rel), OP_BL_LO(rel)); + } else { + printf("asm_thumb_bl: branch does not fit in 23 bits\n"); + } +} + #define OP_BLX(reg) (0x4780 | ((reg) << 3)) #define OP_SVC(arg) (0xdf00 | (arg)) |