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| author | Pierre Langlois <pierre.langlois@embecosm.com> | 2014-07-25 14:45:03 +0100 |
|---|---|---|
| committer | Pierre Langlois <pierre.langlois@embecosm.com> | 2014-07-25 15:03:29 +0100 |
| commit | 7d0d9d2bee341b1e88c559c476f15fc24b6de346 (patch) | |
| tree | f6781f9824890f6f6ccad55a60a2b8e257ca6ee8 /gdb/avr-tdep.c | |
| parent | c3f814a14336b9d395f3abad739592929e2faaa0 (diff) | |
| download | gdb-7d0d9d2bee341b1e88c559c476f15fc24b6de346.zip gdb-7d0d9d2bee341b1e88c559c476f15fc24b6de346.tar.gz gdb-7d0d9d2bee341b1e88c559c476f15fc24b6de346.tar.bz2 | |
Clarify the address and pointer conversions on AVR.
This patch adds additional comments about the conversion of addresses to
pointers and vice-versa on AVR.
Special conversion needs to be done when dealing with an address in the
flash address space, where both code and read-only data can be stored.
Code and data pointers to flash are not addressed the same way:
A code pointer is 16 bit addressed. A data pointer is 8 bit addressed,
even if the data is in flash.
2014-07-25 Pierre Langlois <pierre.langlois@embecosm.com>
* avr-tdep.c (avr_address_to_pointer): Clarify the conversion in the
comments.
(avr_pointer_to_address): Likewise.
Diffstat (limited to 'gdb/avr-tdep.c')
| -rw-r--r-- | gdb/avr-tdep.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/gdb/avr-tdep.c b/gdb/avr-tdep.c index be0b543..1f268f2 100644 --- a/gdb/avr-tdep.c +++ b/gdb/avr-tdep.c @@ -308,7 +308,7 @@ avr_address_to_pointer (struct gdbarch *gdbarch, /* Is it a data address in flash? */ if (AVR_TYPE_ADDRESS_CLASS_FLASH (type)) { - /* A data address in flash is always byte addressed. */ + /* A data pointer in flash is byte addressed. */ store_unsigned_integer (buf, TYPE_LENGTH (type), byte_order, avr_convert_iaddr_to_raw (addr)); } @@ -316,8 +316,8 @@ avr_address_to_pointer (struct gdbarch *gdbarch, else if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC || TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD) { - /* A code address, either a function pointer or the program counter, is - word (16 bits) addressed. */ + /* A code pointer is word (16 bits) addressed. We shift the address down + by 1 bit to convert it to a pointer. */ store_unsigned_integer (buf, TYPE_LENGTH (type), byte_order, avr_convert_iaddr_to_raw (addr >> 1)); } @@ -339,12 +339,19 @@ avr_pointer_to_address (struct gdbarch *gdbarch, /* Is it a data address in flash? */ if (AVR_TYPE_ADDRESS_CLASS_FLASH (type)) - return avr_make_iaddr (addr); + { + /* A data pointer in flash is already byte addressed. */ + return avr_make_iaddr (addr); + } /* Is it a code address? */ else if (TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_FUNC || TYPE_CODE (TYPE_TARGET_TYPE (type)) == TYPE_CODE_METHOD || TYPE_CODE_SPACE (TYPE_TARGET_TYPE (type))) - return avr_make_iaddr (addr << 1); + { + /* A code pointer is word (16 bits) addressed so we shift it up + by 1 bit to convert it to an address. */ + return avr_make_iaddr (addr << 1); + } else return avr_make_saddr (addr); } |