X-Git-Url: http://git.joshuawise.com/fpgaboy.git/blobdiff_plain/df770340caf8ecd26a55179484edb507082bd5c6..77ab69d7bb0902e6ebf0994159ed2205f8413e34:/insn_ret-retcc.v diff --git a/insn_ret-retcc.v b/insn_ret-retcc.v index ef89003..dab27c3 100644 --- a/insn_ret-retcc.v +++ b/insn_ret-retcc.v @@ -1,30 +1,20 @@ `ifdef EXECUTE `INSN_RET,`INSN_RETCC: begin case (cycle) - 0: begin - rd <= 1; - address <= {registers[`REG_SPH],registers[`REG_SPL]}; - end + 0: `EXEC_READ(`_SP) 1: begin // SPECIAL CASE: cycle does NOT increase linearly with ret! - `EXEC_INC_PC; // cycle 1 is skipped if we are not retcc + `EXEC_INC_PC // cycle 1 is skipped if we are not retcc case (opcode[4:3]) - `INSN_cc_NZ: if (registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end - `INSN_cc_Z: if (~registers[`REG_F][7]) begin `EXEC_NEWCYCLE; end - `INSN_cc_NC: if (registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end - `INSN_cc_C: if (~registers[`REG_F][4]) begin `EXEC_NEWCYCLE; end + `INSN_cc_NZ: if (`_F[7]) `EXEC_NEWCYCLE + `INSN_cc_Z: if (~`_F[7]) `EXEC_NEWCYCLE + `INSN_cc_NC: if (`_F[4]) `EXEC_NEWCYCLE + `INSN_cc_C: if (~`_F[4]) `EXEC_NEWCYCLE endcase - rd <= 1; - address <= {registers[`REG_SPH],registers[`REG_SPL]}; - end - 2: begin - rd <= 1; - address <= {registers[`REG_SPH],registers[`REG_SPL]} + 1; + `EXEC_READ(`_SP) // retry the read end + 2: `EXEC_READ(`_SP + 1) 3: begin /* twiddle thumbs */ end - 4: begin - `EXEC_NEWCYCLE; - // do NOT increment PC! - end + 4: `EXEC_NEWCYCLE endcase end `endif @@ -35,11 +25,10 @@ 0: if (opcode[0]) // i.e., not RETCC cycle <= 1; // Skip cycle 1; it gets incremented on the next round. 1: begin /* Nothing need happen here. */ end - 2: registers[`REG_PCL] <= rdata; - 3: registers[`REG_PCH] <= rdata; + 2: `_PCL <= rdata; + 3: `_PCH <= rdata; 4: begin - {registers[`REG_SPH],registers[`REG_SPL]} <= - {registers[`REG_SPH],registers[`REG_SPL]} + 2; + `_SP <= `_SP + 2; if (opcode[4] && opcode[0]) /* RETI */ ie <= 1; end