/* 8085 opcode-field and object-byte checks */
kill(all)$
display2d:false$
print("8085 OPCODES, OPERANDS, MNEMONICS AND MACHINE CODE")$

/* Register codes: B,C,D,E,H,L,M,A = 0,...,7. */
mov_opcode(dst,src) := 64 + 8*dst + src$
mvi_opcode(dst) := 6 + 8*dst$
alu_opcode(group,src) := 128 + 8*group + src$
lxi_opcode(rp) := 1 + 16*rp$
jcc_opcode(cond) := 194 + 8*cond$
rst_opcode(n) := 199 + 8*n$
low_byte(n) := mod(n,256)$
high_byte(n) := floor(n/256)$

/* MOV A,C = 01 111 001 = 79H; MOV M,M field collides with HLT 76H. */
mov_ac : mov_opcode(7,1)$
mov_mm : mov_opcode(6,6)$
print("MOV A,C and nominal MOV M,M opcodes (decimal) =",mov_ac,mov_mm)$
if not is([mov_ac,mov_mm]=[121,118]) then error("MOV encoding failed")$

/* MVI D,5AH begins 16H and is followed by 5AH. */
mvi_d : mvi_opcode(2)$
data_5a : 5*16+10$
print("MVI D,5AH bytes (decimal) =",mvi_d,data_5a)$
if not is([mvi_d,data_5a]=[22,90]) then error("MVI encoding failed")$

/* ALU groups: ADD=0, ADC=1, SUB=2, SBB=3, ANA=4, XRA=5, ORA=6, CMP=7. */
add_m : alu_opcode(0,6)$
cmp_a : alu_opcode(7,7)$
xra_m : alu_opcode(5,6)$
print("ADD M, CMP A, XRA M opcodes (decimal) =",add_m,cmp_a,xra_m)$
if not is([add_m,cmp_a,xra_m]=[134,191,174]) then error("ALU encoding failed")$

/* LXI H,2050H: RP=2, opcode 21H, then low and high operand bytes. */
word : 2*16^3 + 5*16$
lxi_h : lxi_opcode(2)$
print("LXI H,2050H bytes (decimal) =",lxi_h,low_byte(word),high_byte(word))$
if not is([lxi_h,low_byte(word),high_byte(word)]=[33,80,32]) then error("LXI encoding failed")$

/* JNZ condition=0; JZ condition=1. RST 5 vectors to 8*5=0028H. */
jnz : jcc_opcode(0)$
jz : jcc_opcode(1)$
rst5 : rst_opcode(5)$
vector5 : 8*5$
print("JNZ, JZ, RST 5 opcodes and vector (decimal) =",jnz,jz,rst5,vector5)$
if not is([jnz,jz,rst5,vector5]=[194,202,239,40]) then error("branch encoding failed")$

/* Listing length: 2+1+2+3 bytes from 2000H ends at 2008H. */
start : 2*16^3$
next_address : start + 2+1+2+3$
print("Next address after the worked listing (decimal) =",next_address)$
if not is(next_address=8200) then error("listing address calculation failed")$

print("All opcode-field checks passed.")$
quit();