collapseos/blk/753
Virgil Dupras a7dcb522c2 Make br cells 1 byte wide
The 1 byte limitation has been effective for a while now, but I
hadn't made the move yet, I wanted to see if the limitation would
cause me problems. It doesn't.

Doing this now slightly facilitates the IY->BC move in z80.

Bootstrapping: if you try to recreate the CVM binary from the
previous commit with this code, you'll have bootstrapping problems.
The first bootstrap will compile a binary with 2-bytes wide cells
but branching conditionals that yields 1-byte cells. That's bad.

I got around the issue by temporarily inserting a "397 399 LOADR"
instruction in cvm/xcomp.fs, right before the xcomp overrides. This
way, I force 1-byte cells everywhere on the first compiliation,
which then allows me to apply the logic change in cvm/vm.c and have
a properly running binary.
2020-07-06 07:27:50 -04:00

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: OP1 CREATE C, DOES> C@ A, ;
0xc3 OP1 RETn, 0xfa OP1 CLI, 0xfb OP1 STI,
0xf4 OP1 HLT, 0xfc OP1 CLD, 0xfd OP1 STD,
0x90 OP1 NOP, 0x98 OP1 CBW,
0xf3 OP1 REPZ, 0xf2 OP1 REPNZ, 0xac OP1 LODSB,
0xad OP1 LODSW, 0xa6 OP1 CMPSB, 0xa7 OP1 CMPSW,
0xa4 OP1 MOVSB, 0xa5 OP1 MOVSW, 0xae OP1 SCASB,
0xaf OP1 SCASW, 0xaa OP1 STOSB, 0xab OP1 STOSW,
( no argument, jumps with relative addrs are special )
0xeb OP1 JMPs, 0xe9 OP1 JMPn, 0x74 OP1 JZ,
0x75 OP1 JNZ, 0x72 OP1 JC, 0x73 OP1 JNC,
0xe8 OP1 CALLn,
: OP1r CREATE C, DOES> C@ + A, ;
0x40 OP1r INCx, 0x48 OP1r DECx,
0x58 OP1r POPx, 0x50 OP1r PUSHx,