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DAA and DAS algorithms for x86_64

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This commit is contained in:
Aaron Culliney 2014-06-13 23:48:30 -07:00
parent 2def12c703
commit 995643dfa2
2 changed files with 90 additions and 11 deletions
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3
src/x86/cpu-regs.h
View File

@ -20,6 +20,9 @@
#define PC_Reg %si /* 6502 Program Counter */
#define EffectiveAddr %di /* Effective address */
#define X86_CF_Bit 0x0 /* x86 carry */
#define X86_AF_Bit 0x4 /* x86 adj (nybble carry) */
#if __LP64__
# define SZ_PTR 8
# define ROR_BIT 63

98
src/x86/cpu.S
View File

@ -127,7 +127,7 @@
#define FlagNVZC \
pushfLQ; \
popLQ _XAX; \
andLQ $0x08C1,_XAX; \
andLQ $(N_Flag|(V_Flag<<8)|Z_Flag|C_Flag),_XAX; \
andb $~(N_Flag|V_Flag|Z_Flag|C_Flag), F_Reg; \
orb %ah, F_Reg; \
orb %al, F_Reg;
@ -445,13 +445,50 @@ E(op_ADC_dec)
DebugBCDCheck
bt $C_Flag_Bit, AF_Reg_X
adcb A_Reg, %al
#ifdef __LP64__
#warning TODO FIXME das instruction
#else
#if !defined(__LP64__)
daa
#endif
movb %al, A_Reg
FlagNVZC
#else
// DAA algorithm : http://www.ray.masmcode.com/BCDdaa.html
// CF_old = CF
// IF (al AND 0Fh > 9) or (the Auxilliary Flag is set)
// al = al + 6
// CF = CF (automagically) or CF_old
// AF set (automagically)
// ENDIF
// IF (al > 99h) or (Carry Flag is set)
// al = al + 60h
// CF set
// ENDIF
pushq _XBX
pushfq
popq _XBX
andb $~(N_Flag|V_Flag|Z_Flag|C_Flag), F_Reg
movb %al, %ah
andb $0x0f, %ah
cmpb $9, %ah
jg _daa_lo_nyb
btq $X86_AF_Bit, _XBX
jnc _daa_next0
_daa_lo_nyb: addb $6, %al // adjust lo nybble
jc _daa_hi_nyb
_daa_next0: btq $X86_CF_Bit, _XBX
jc _daa_hi_nyb
xorb %ah, %ah
cmpw $0x99, %ax
jle _daa_next1
_daa_hi_nyb: addb $0x60, %al // adjust hi nybble
orb $C_Flag, F_Reg // FlagC
_daa_next1: testq $0x80, %rax
jz _daa_next2
orb $N_Flag, F_Reg // FlagN
_daa_next2: testq $0xFF, %rax
jnz _daa_finish
orb $Z_Flag, F_Reg // FlagZ
_daa_finish: popq _XBX
movb %al, A_Reg
#endif
Continue
E(op_ADC_imm) // 0x69
@ -1562,18 +1599,57 @@ E(op_SBC_dec)
incb DebugCycleCount // +1 cycle
GetFromEA_B
DebugBCDCheck
bt $C_Flag_Bit, AF_Reg_X
cmc
btc $C_Flag_Bit, AF_Reg_X
xchgb A_Reg, %al
#if !defined(__LP64__)
sbbb A_Reg, %al
#ifdef __LP64__
#warning TODO FIXME das instruction
#else
das
#endif
movb %al, A_Reg
cmc
FlagNVZC
#else
cmc
sbbb A_Reg, %al
// DAS algorithm : http://www.ray.masmcode.com/BCDdas.html
// CF_old = CF
// IF (al AND 0Fh > 9) or (the Auxilliary Flag is set)
// al = al - 6
// CF = CF (automagically) or CF_old
// AF set (automagically)
// ENDIF
// IF (al > 99h) or (Carry Flag is set)
// al = al - 60h
// ^CF set
// ENDIF
pushq _XBX
pushfq
popq _XBX
andb $~(N_Flag|V_Flag|Z_Flag), F_Reg
orb $C_Flag, F_Reg
movb %al, %ah
andb $0x0f, %ah
cmpb $9, %ah
jg _das_lo_nyb
btq $X86_AF_Bit, _XBX
jnc _das_next0
_das_lo_nyb: subb $6, %al // adjust lo nybble
jc _das_hi_nyb
_das_next0: btq $X86_CF_Bit, _XBX
jc _das_hi_nyb
xorb %ah, %ah
cmpw $0x99, %ax
jle _das_next1
_das_hi_nyb: subb $0x60, %al // adjust hi nybble
andb $~C_Flag, F_Reg // !FlagC
_das_next1: testq $0x80, %rax
jz _das_next2
orb $N_Flag, F_Reg // FlagN
_das_next2: testq $0xFF, %rax
jnz _das_finish
orb $Z_Flag, F_Reg // FlagZ
_das_finish: popq _XBX
movb %al, A_Reg
#endif
Continue
E(op_SBC_imm) // 0xe9