Previously the MPW linker script would generate a secondary script to be
executed. This was unnecessarily complicated, and it left some junk in
the build tree.
Whenever a field was added to the end of the Primary System Area (PSA)
record, the offsets of all other fields would change. When reversing NK
version 02.27, I noticed that 32 bytes had been added to the end of the
PSA between 02.27 and 02.28. To build a byte-perfect 02.27, all
references to PSA fields must therefore use the record definition in
NKPublic.s instead of a numeric offset.
In this commit, all PSA references are identified by field name (_FFF if
the field has not yet been reversed).
These + and - characters in a branch mnemonic can cause the assembler to
produce conditional branch instructions with that hint the branch
predictor. The default for forward branches is -, and for backward
branches is +. If a mnemonic is issued with the opposite sign, then bit
10 of the instruction (the LSB of the BO field) is set.
My long-retired "ppcdisasm" script inserted these hints unconditionally,
despite 98% of them not being required. The code is much cleaner now.
I read in some old MPW release notes that PPCAsm and PPCLink together
exhibit a quirk when linking conditional branches to imported symbols.
PPCAsm always assembles these conditional branches as if they were
forward branches (that is, a + hint will always set the hint bit, and a
- hint will never). I hoped to use this property to divine whether the
NanoKernel was linked from one or many assembly files, but I was
frustrated by the lack of conditional branches between files.
Version 02.11 of the NanoKernel prints an annotated crash dump of the
EDP. This version has been partly reversed (using Hopper!), and the
sometimes-cryptic EDP field names have been added to EmulatorPublic.a.
