SH7261 datasheet(105/1348 Pages) RENESAS

105 / 1348 page

Section 3 Floating-Point Unit (FPU)

Rev. 2.00 Sep. 07, 2007 Page 73 of 1312

REJ09B0320-0200

Bit

Bit Name

Initial

Value

R/W

Description

17 to 12

Cause

All 0

R/W

11 to 7

Enable

All 0

R/W

6 to 2

Flag

All 0

R/W

FPU Exception Cause Field

FPU Exception Enable Field

FPU Exception Flag Field

When an FPU exception occurs, the bits corresponding

to the FPU exception cause field and FPU exception

flag field are set to 1. Each time an FPU operation

instruction is executed, the FPU exception cause field

is cleared to 0. The FPU exception flag field remains

set to 1 until it is cleared to 0 by software.

For bit allocations of each field, see table 3.3.

RM1

RM0

R/W

Rounding Mode

These bits select the rounding mode.

00: Round to Nearest

01: Round to Zero

10: Reserved

11: Reserved

Table 3.3

Bit Allocation for FPU Exception Handling

Field Name

FPU

Error (E)

Invalid

Operation (V)

Division

by Zero (Z)

Overflow

(O)

Underflow

(U)

Inexact

(I)

Cause

FPU exception

cause field

Bit 17

Bit 16

Bit 15

Bit 14

Bit 13

Bit 12

Enable

FPU exception

enable field

None

Bit 11

Bit 10

Bit 9

Bit 8

Bit 7

Flag

FPU exception flag

field

None

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Note:

No FPU error occurs in the SH2A-FPU.

3.3.3

Floating-Point Communication Register (FPUL)

Information is transferred between the FPU and CPU via FPUL. FPUL is a 32-bit system register

that is accessed from the CPU side by means of LDS and STS instructions. For example, to

convert the integer stored in general register R1 to a single-precision floating-point number, the

processing flow is as follows:

→ (LDS instruction) → FPUL → (single-precision FLOAT instruction) → FR1

SH7261 датащи(PDF) 105 Page - Renesas Technology Corp

SH7261 датащи(HTML) 105 Page - Renesas Technology Corp

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL