Subtraction instructions test bench
From Zet
This example tests these instructions:
- sub
- sbb
- dec
Code
.code16 start: movw $160, %sp # sub word tests movw $0x0001, %ax movw $0x0002, %bx subw %bx, %ax movw %ax, (0) movw %bx, (2) pushf movw $0xffff, %dx movw $0xffff, (4) subw %dx, (4) movw %dx, (6) pushf movw $0xffff, %cx movw $0x0001, (8) subw (8), %cx movw %cx, (10) pushf movw $0x8000, %ax subw $0x0001, %ax movw %ax, (12) pushf movw $0x8000, %bp .byte 0x83,0xed,0xff movw %bp, (14) pushf movw $0x7f81, %si subw $0x903c, %si movw %si, (16) pushf movw $0xefc3, (18) subw $0xc664, (18) pushf movw $0xe933, (20) .word 0x2e83, 0x0014 .byte 0x64 pushf # sub byte tests movb $0x01, (22) subb $0x02, (22) pushf movb $0xff, %dh subb $0xff, %dh movw %dx, (23) pushf movb $0xff, %al subb $0x01, %al movw %ax, (25) pushf movb $0x80, (27) movb $0x01, %ch subb (27), %ch movw %cx, (28) pushf movb $0x80, %bl movb $0x7f, (30) subb %bl, (30) movw %bx, (31) pushf movb $0xbc, %al movb $0x8e, %ah subb %al, %ah movw %ax, (33) pushf # sbb word tests movw $0x0001, %ax movw $0x0002, %bx sbbw %ax, %bx movw %ax, (35) movw %bx, (37) pushf movw $0xffff, %dx movw $0xffff, (39) sbbw %dx, (39) movw %dx, (41) pushf movw $0xffff, %cx movw $0x0001, (43) sbbw (43), %cx movw %cx, (45) pushf movw $0x8000, %ax sbbw $0x0001, %ax movw %ax, (47) pushf movw $0x8000, %bp .byte 0x83,0xdd,0xff movw %bp, (49) pushf movw $0x52c3, %si sbbw $0xe248, %si movw %si, (51) pushf movw $0xe74c, (53) sbbw $0x22c0, (53) pushf movw $0xfd85, (55) .word 0x1e83, 0x0037 .byte 0xf5 pushf # sbb byte tests movb $0x01, (57) sbbb $0x02, (57) pushf movb $0xff, %dh sbbb $0xff, %dh movw %dx, (58) pushf movb $0xff, %al sbbb $0x01, %al movw %ax, (60) pushf movb $0x80, (62) movb $0x01, %ch sbbb (62), %ch movw %cx, (63) pushf movb $0x80, %bl movb $0xff, (65) sbbb %bl, (65) movw %bx, (66) pushf movb $0xb9, %al movb $0xd3, %ah sbbb %al, %ah movw %ax, (68) pushf # dec word tests movw $0x0000, %di decw %di movw %di, (70) pushf movw $0x8000, %bp .byte 0xff, 0xcd movw %bp, (72) pushf movw $0x7412, (74) decw (74) pushf # dec byte tests movb $0x00, %dl decb %dl movw %dx, (76) pushf movb $0x80, (77) decb (77) pushf movb $0xb5, (78) decb (78) pushf hlt .org 65520 jmp start .org 65535 .byte 0xff
Results
Memory contents at the end should be:
0x00: 0xffff 0x0002 0x0000 0xffff 0x0001 0xfffe 0x7fff 0x8001 0x10: 0xef45 0x295f 0xe8cf 0xffff 0xfe00 0x807f 0x81fe 0x80ff 0x20: 0xbc00 0x01d2 0x0000 0x0000 0xff00 0x01ff 0xfe00 0xffff 0x30: 0x017f 0x7a80 0x8b70 0x90c4 0xfefd 0xffff 0x7ffd 0xfe80 0x40: 0x7e81 0x0080 0x1ab9 0xffff 0x7fff 0x7411 0x7fff 0xXXb4 0x50: 0xXXXX 0xXXXX 0xXXXX 0xXXXX 0xXXXX 0xXXXX 0x0086 0x0812 0x60: 0x0096 0x0006 0x0816 0x0096 0x0012 0x0006 0x0887 0x0082 0x70: 0x0097 0x0093 0x0087 0x0086 0x0013 0x0093 0x0816 0x0082 0x80: 0x0046 0x0046 0x0087 0x0887 0x0887 0x0082 0x0046 0x0097 0x90: 0x0096 0x0016 0x0893 0x0093 0x0816 0x0082 0x0046 0x0097
