diff options
Diffstat (limited to 'gdb/value.c')
| -rw-r--r-- | gdb/value.c | 145 |
1 files changed, 122 insertions, 23 deletions
diff --git a/gdb/value.c b/gdb/value.c index ee53914707a..a15315ed4b5 100644 --- a/gdb/value.c +++ b/gdb/value.c @@ -2532,30 +2532,24 @@ value_fn_field (struct value **arg1p, struct fn_field *f, } -/* Unpack a bitfield of the specified FIELD_TYPE, from the anonymous - object at VALADDR. The bitfield starts at BITPOS bits and contains - BITSIZE bits. - Extracting bits depends on endianness of the machine. Compute the - number of least significant bits to discard. For big endian machines, - we compute the total number of bits in the anonymous object, subtract - off the bit count from the MSB of the object to the MSB of the - bitfield, then the size of the bitfield, which leaves the LSB discard - count. For little endian machines, the discard count is simply the - number of bits from the LSB of the anonymous object to the LSB of the - bitfield. +/* Helper function for both unpack_value_bits_as_long and + unpack_bits_as_long. See those functions for more details on the + interface; the only difference is that this function accepts either + a NULL or a non-NULL ORIGINAL_VALUE. */ - If the field is signed, we also do sign extension. */ - -LONGEST -unpack_bits_as_long (struct type *field_type, const gdb_byte *valaddr, - int bitpos, int bitsize) +static int +unpack_value_bits_as_long_1 (struct type *field_type, const gdb_byte *valaddr, + int embedded_offset, int bitpos, int bitsize, + const struct value *original_value, + LONGEST *result) { enum bfd_endian byte_order = gdbarch_byte_order (get_type_arch (field_type)); ULONGEST val; ULONGEST valmask; int lsbcount; int bytes_read; + int read_offset; /* Read the minimum number of bytes required; there may not be enough bytes to read an entire ULONGEST. */ @@ -2565,7 +2559,14 @@ unpack_bits_as_long (struct type *field_type, const gdb_byte *valaddr, else bytes_read = TYPE_LENGTH (field_type); - val = extract_unsigned_integer (valaddr + bitpos / 8, + read_offset = bitpos / 8; + + if (original_value != NULL + && !value_bytes_available (original_value, embedded_offset + read_offset, + bytes_read)) + return 0; + + val = extract_unsigned_integer (valaddr + embedded_offset + read_offset, bytes_read, byte_order); /* Extract bits. See comment above. */ @@ -2591,20 +2592,118 @@ unpack_bits_as_long (struct type *field_type, const gdb_byte *valaddr, } } } - return (val); + + *result = val; + return 1; } -/* Unpack a field FIELDNO of the specified TYPE, from the anonymous object at - VALADDR. See unpack_bits_as_long for more details. */ +/* Unpack a bitfield of the specified FIELD_TYPE, from the object at + VALADDR + EMBEDDED_OFFSET, and store the result in *RESULT. + VALADDR points to the contents of ORIGINAL_VALUE, which must not be + NULL. The bitfield starts at BITPOS bits and contains BITSIZE + bits. -LONGEST -unpack_field_as_long (struct type *type, const gdb_byte *valaddr, int fieldno) + Returns false if the value contents are unavailable, otherwise + returns true, indicating a valid value has been stored in *RESULT. + + Extracting bits depends on endianness of the machine. Compute the + number of least significant bits to discard. For big endian machines, + we compute the total number of bits in the anonymous object, subtract + off the bit count from the MSB of the object to the MSB of the + bitfield, then the size of the bitfield, which leaves the LSB discard + count. For little endian machines, the discard count is simply the + number of bits from the LSB of the anonymous object to the LSB of the + bitfield. + + If the field is signed, we also do sign extension. */ + +int +unpack_value_bits_as_long (struct type *field_type, const gdb_byte *valaddr, + int embedded_offset, int bitpos, int bitsize, + const struct value *original_value, + LONGEST *result) +{ + gdb_assert (original_value != NULL); + + return unpack_value_bits_as_long_1 (field_type, valaddr, embedded_offset, + bitpos, bitsize, original_value, result); + +} + +/* Unpack a field FIELDNO of the specified TYPE, from the object at + VALADDR + EMBEDDED_OFFSET. VALADDR points to the contents of + ORIGINAL_VALUE. See unpack_value_bits_as_long for more + details. */ + +static int +unpack_value_field_as_long_1 (struct type *type, const gdb_byte *valaddr, + int embedded_offset, int fieldno, + const struct value *val, LONGEST *result) { int bitpos = TYPE_FIELD_BITPOS (type, fieldno); int bitsize = TYPE_FIELD_BITSIZE (type, fieldno); struct type *field_type = TYPE_FIELD_TYPE (type, fieldno); - return unpack_bits_as_long (field_type, valaddr, bitpos, bitsize); + return unpack_value_bits_as_long_1 (field_type, valaddr, embedded_offset, + bitpos, bitsize, val, + result); +} + +/* Unpack a field FIELDNO of the specified TYPE, from the object at + VALADDR + EMBEDDED_OFFSET. VALADDR points to the contents of + ORIGINAL_VALUE, which must not be NULL. See + unpack_value_bits_as_long for more details. */ + +int +unpack_value_field_as_long (struct type *type, const gdb_byte *valaddr, + int embedded_offset, int fieldno, + const struct value *val, LONGEST *result) +{ + gdb_assert (val != NULL); + + return unpack_value_field_as_long_1 (type, valaddr, embedded_offset, + fieldno, val, result); +} + +/* Unpack a field FIELDNO of the specified TYPE, from the anonymous + object at VALADDR. See unpack_value_bits_as_long for more details. + This function differs from unpack_value_field_as_long in that it + operates without a struct value object. */ + +LONGEST +unpack_field_as_long (struct type *type, const gdb_byte *valaddr, int fieldno) +{ + LONGEST result; + + unpack_value_field_as_long_1 (type, valaddr, 0, fieldno, NULL, &result); + return result; +} + +/* Return a new value with type TYPE, which is FIELDNO field of the + object at VALADDR + EMBEDDEDOFFSET. VALADDR points to the contents + of VAL. If the VAL's contents required to extract the bitfield + from are unavailable, the new value is correspondingly marked as + unavailable. */ + +struct value * +value_field_bitfield (struct type *type, int fieldno, + const gdb_byte *valaddr, + int embedded_offset, const struct value *val) +{ + LONGEST l; + + if (!unpack_value_field_as_long (type, valaddr, embedded_offset, fieldno, + val, &l)) + { + struct type *field_type = TYPE_FIELD_TYPE (type, fieldno); + struct value *retval = allocate_value (field_type); + mark_value_bytes_unavailable (retval, 0, TYPE_LENGTH (field_type)); + return retval; + } + else + { + return value_from_longest (TYPE_FIELD_TYPE (type, fieldno), l); + } } /* Modify the value of a bitfield. ADDR points to a block of memory in |