jb302@28: /* mem.c
jb302@28:  * functions for accessing emulator memory */
jb302@28: #include "mem.h"
jb302@28: 
jb302@28: /* get flag value
jb302@28:  * if invalid flag is requested value is 0 */
jb302@28: BYTE
jb302@28: get_flag(BYTE flag) {
jb302@28:     if (flag > 7) {
jb302@28:         return 0;
jb302@28:     }
jb302@28:     else {
jb302@28:         return GBIT(flags, flag);
jb302@28:     }
jb302@28: }
jb302@28: 
jb302@28: /*  set flag to 0 if on == 0
jb302@28:  *  otherwise set flag to 1 */
jb302@28: void
jb302@28: set_flag(BYTE flag, BYTE on) {
jb302@28:     if (flag <= 7) {
jb302@28:         switch (on) {
jb302@28:             
jb302@28:             case 0:
jb302@28:                 flags = CBIT(flags, flag);
jb302@28: 
jb302@28:             default:
jb302@28:                 flags = SBIT(flags, flag);
jb302@28:         }
jb302@28:     }
jb302@28: }
jb302@28: 
jb302@28: WIDE
jb302@28: get_wide(BYTE reg) {
jb302@28:     /* low | (high << 8) */
jb302@28:     return (regs[reg + 12] | (regs[reg + 4] << 8));
jb302@28: }
jb302@28: 
jb302@28: void
jb302@28: set_wide(BYTE reg, WIDE val) {
jb302@28:     regs[reg + 4] = (val >> 8) & 0xFF; /* high */
jb302@28:     regs[reg + 12] = val & 0xFF; /* low */
jb302@28: }
jb302@28: 
jb302@28: void 
jb302@28: inc_pc(BYTE n) {
jb302@28:     if ((regs[PCL] + n) > 0xFF) {
jb302@28:         regs[PCH]++;
jb302@28:     }
jb302@28:     regs[PCL] += n;
jb302@28: }
jb302@28: 
jb302@28: BYTE 
jb302@28: fetch(void) {
jb302@28:     BYTE val = mem[get_wide(PC)];
jb302@28:     inc_pc(1);
jb302@28:     return val;
jb302@28: }
jb302@28: 
jb302@28: WIDE
jb302@28: fetch_wide(void) {
jb302@28:     WIDE val = mem[get_wide(PC)] | (mem[get_wide(PC + 1)] << 8);
jb302@28:     inc_pc(2);
jb302@28:     return val;
jb302@28: }
jb302@28: 
jb302@28: