Renesas SH7781 - Manual (Page 61)

2. Programming Model
Rev.1.00 Jan. 10, 2008 Page 31 of 1658
REJ09B0261-0100
Note on Programming: As the user's R0 to R7 are assigned to R0_BANK0 to R7_BANK0, and
after an exception or interrupt R0 to R7 are assigned to R0_BANK1 to
R7_BANK1, it is not necessary for the interrupt handler to save and
restore the user's R0 to R7 (R0_BANK0 to R7_BANK0).
2.2.3 Floating-Point Registers
Figure 2.4 shows the floating-point register configuration. There are thirty-two 32-bit floating-
point registers, FPR0_BANK0 to FPR15_BANK0, AND FPR0_BANK1 to FPR15_BANK1,
comprising two banks. These registers are referenced as FR0 to FR15, DR0/2/4/6/8/10/12/14,
FV0/4/8/12, XF0 to XF15, XD0/2/4/6/8/10/12/14, or XMTRX. Reference names of each register
are defined depending on the state of the FR bit in FPSCR (see figure 2.4).
1. Floating-point registers, FPRn_BANKj (32 registers)
FPR0_BANK0 to FPR15_BANK0
FPR0_BANK1 to FPR15_BANK1
2. Single-precision floating-point registers, FRi (16 registers)
When FPSCR.FR = 0, FR0 to FR15 are assigned to FPR0_BANK0 to FPR15_BANK0;
when FPSCR.FR = 1, FR0 to FR15 are assigned to FPR0_BANK1 to FPR15_BANK1.
3. Double-precision floating-point registers or single-precision floating-point registers, DRi (8
registers): A DR register comprises two FR registers.
DR0 = {FR0, FR1}, DR2 = {FR2, FR3}, DR4 = {FR4, FR5}, DR6 = {FR6, FR7},
DR8 = {FR8, FR9}, DR10 = {FR10, FR11}, DR12 = {FR12, FR13}, DR14 = {FR14, FR15}
4. Single-precision floating-point vector registers, FVi (4 registers): An FV register comprises
four FR registers.
FV0 = {FR0, FR1, FR2, FR3}, FV4 = {FR4, FR5, FR6, FR7},
FV8 = {FR8, FR9, FR10, FR11}, FV12 = {FR12, FR13, FR14, FR15}
5. Single-precision floating-point extended registers, XFi (16 registers)
When FPSCR.FR = 0, XF0 to XF15 are assigned to FPR0_BANK1 to FPR15_BANK1;
when FPSCR.FR = 1, XF0 to XF15 are assigned to FPR0_BANK0 to FPR15_BANK0.
6. Double-precision floating-point extended registers, XDi (8 registers): An XD register
comprises two XF registers.
XD0 = {XF0, XF1}, XD2 = {XF2, XF3}, XD4 = {XF4, XF5}, XD6 = {XF6, XF7},
XD8 = {XF8, XF9}, XD10 = {XF10, XF11}, XD12 = {XF12, XF13}, XD14 = {XF14, XF15}