diff --git a/apps/zasm/avr.asm b/apps/zasm/avr.asm index 9ba5105..0dde676 100644 --- a/apps/zasm/avr.asm +++ b/apps/zasm/avr.asm @@ -121,7 +121,14 @@ instrNames: ; index (1-based, 0 means no arg) in the argSpecs table. High nibble is for ; flags. Meaning: ; -; (None for now) +; Bit 7: Arguments swapped. For example, if we have this bit set on the argspec +; row 'A', 'R', then what will actually be read is 'R', 'A'. The +; arguments destination will be, hum, de-swapped, that is, 'A' is going +; in H and 'R' is going in L. This is used, for example, with IN and OUT. +; IN has a Rd(5), A(6) signature. OUT could have the same signature, but +; AVR's mnemonics has those args reversed for more consistency +; (destination is always the first arg). The goal of this flag is to +; allow this kind of syntactic sugar with minimal complexity. ; In the same order as in instrNames instrTbl: @@ -157,8 +164,8 @@ instrTbl: .db 0x00, 0b11010000, 0x00 ; RCALL .db 0x00, 0b11000000, 0x00 ; RJMP ; IN and OUT -.db 0x08, 0b10110000, 0x00 ; IN -.db 0x07, 0b10111000, 0x00 ; OUT +.db 0x07, 0b10110000, 0x00 ; IN +.db 0x87, 0b10111000, 0x00 ; OUT (args reversed) ; no arg .db 0x00, 0b10010101, 0b10011000 ; BREAK .db 0x00, 0b10010100, 0b10001000 ; CLC @@ -273,6 +280,8 @@ parseInstruction: ld a, (hl) ld h, d ld l, a ; H and L contain specs now + bit 7, (ix) + call nz, .swapHL ; Bit 7 set, swap H and L call _parseArgs ret nz .noarg: @@ -280,6 +289,8 @@ parseInstruction: ; (IX) is table row ; Parse arg values now in H and L ; InstrID is E + bit 7, (ix) + call nz, .swapHL ; Bit 7 set, swap H and L again! ld a, e ; InstrID cp I_ANDI jr c, .spitRd5Rr5 @@ -289,9 +300,8 @@ parseInstruction: jr c, .spitRdBit cp I_IN jr c, .spitK12 - jp z, .spitIN - cp I_OUT - jp z, .spitOUT + cp I_BREAK + jp c, .spitINOUT cp I_ASR jp c, .spit ; no arg ; spitRd5 @@ -368,12 +378,7 @@ parseInstruction: or b jp ioPutB -.spitOUT: - ld a, h - ld h, l - ld l, a - ; Continue to spitIN -.spitIN: +.spitINOUT: ; Rd in H, A in L ld a, h call .placeRd @@ -463,6 +468,12 @@ parseInstruction: ld c, a ret +.swapHL: + ld a, h + ld h, l + ld l, a + ret + ; Argspecs: two bytes describing the arguments that are accepted. Possible ; values: ; @@ -486,7 +497,6 @@ argSpecs: .db 'r', 8 ; Rd(4) + K(8) .db 'R', 'b' ; Rd(5) + bit .db 'b', 7 ; bit + k(7) - .db 'A', 'R' ; A(6) + Rr(5) .db 'R', 'A' ; Rd(5) + A(6) ; Parse arguments from I/O according to specs in HL